MATERIALS and GEOENVIRONMENT MATERIALI in GEOOKOLJE RMZ - M&G, Vol. 62, No. 3 pp. 147-210 (2015) Ljubljana, November 2015 RMZ - Materials and Geoenvironment RMZ - Materiali in geookolje ISSN 1408-7073 Old title/Star naslov Mining and Metallurgy Quarterly/Rudarsko-metalurški zbornik ISSN 0035-9645, 1952-1997 Copyright © 2015 RMZ - Materials and Geoenvironment Published by/Izdajatelj Faculty of Natural Sciences and Engineering, University of Ljubljana/ Naravoslovnotehniška fakulteta, Univerza v Ljubljani Associated Publisher/Soizdajatelj Institute for Mining, Geotechnology and Environment, Ljubljana/ Inštitut za rudarstvo, geotehnologijo in okolje Velenje Coal Mine/Premogovnik Velenje Editor-in-Chief/Glavni urednik Peter Fajfar Editorial Manager/Odgovorni urednik Jakob Likar Editorial Board/Uredniški odbor Vlasta Ćosović, Sveučilište u Zagrebu Evgen Dervarič, Univerza v Ljubljani Meta Dobnikar, Ministrstvo za izobraževanje, znanost in šport Jan Falkus, Akademia Górniczno-Hutnicza im. S. Staszica w Krakowie Aleksandar Ganić, Univerzitet u Beogradu Borut Kosec, Univerza v Ljubljani Jakob Likar, Univerza v Ljubljani David John Lowe, British Geological Survey Ilija Mamuzić, Sveučilište u Zagrebu Milan Medved, Premogovnik Velenje Peter Moser, Montanuniversität Leoben Primož Mrvar, Univerza v Ljubljani Heinz Palkowski, Technische Universität Clausthal Daniele Peila, Politecnico di Torino Sebastiano Pelizza, Politecnico di Torino Jože Ratej, Inštitut za rudarstvo, geotehnologijo in okolje v Ljubljani Andrej Šmuc, Univerza v Ljubljani Milan Terčelj, Univerza v Ljubljani Milivoj Vulić, Univerza v Ljubljani Nina Zupančič, Univerza v Ljubljani Franc Zupanič, Univerza v Mariboru Editorial Office/Uredništvo Secretary/Tajnica Ines Langerholc Technical Editor/Tehnična urednica Helena Buh Editor of website/Urednik spletne strani Timotej Verbovšek Editorial Address/Naslov uredništva RMZ - Materials and Geoenvironment Aškerčeva cesta 12, p. p. 312 1001 Ljubljana, Slovenija Tel.: +386 (0)1 470 45 00 Fax.: +386 (0)1 470 45 60 E-mail: rmz-mg@ntf.uni-lj.si Linguistic Advisor/Lektor Jože Gasperič Design and DTP/Oblikovanje, prelom in priprava za tisk IDEJA.si Print/Tisk Birografika BORI, d. o. o. 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Current account/Tekoči račun Nova Ljubljanska banka, d. d., Ljubljana: UJP 01100-6030708186 VAT identification number/Davčna številka 24405388 Online Journal/Elektronska revija www.rmz-mg.com Table of Contents Kazalo Original scientific papers Izvirni znanstveni članki Stochastically improved methodology for probability of success (POS) calculation in 149 hydrocarbon systems Stohastično dopolnjena metodologija računanja verjetnosti uspeha (POS) v ogljikovodičnih sistemih Tomislav Malvić, Josipa Velić Compositional characteristics of the migmatite gneiss around Awo, 157 southwestern Nigeria Značilnosti sestave migmatitnega gnajsa pri Awu v jugozahodni Nigeriji Mustapha T. Jimoh, Anthony T. Bolarinwa, Oluwanifemi O. Ashaye Data preparation for groundwater modelling - Ljubljansko polje aquifer system 167 Priprava podatkov za modeliranje podzemne vode - vodonosni sistem Ljubljansko polje Janja Vrzel, Nives Ogrinc, Goran Vižintin Analyisis of shallow tunnels construction in swelling grounds 175 Analiza gradnje plitvih predorov v nabrekalnih hribinah Jakob Likar, Andrej Likar, Jože Žarn, Tina Marolt Čebašek Professional papers Strokovni članki Geological setting, compositional features and economic evaluation of marble deposits 193 around Alaguntan, southwestern Nigeria Geološka lega, značilnosti sestave in gospodarska ocena nahajališč marmorja v okolici Alaguntana v jugozahodni Nigeriji Olugbenga Okunlola, Hafsat Muritala Historical Review Zgodovinski pregled More than 90 years have passed since the University Ljubljana in Slovenia was founded in 1919. Technical fields were united in the School of Engineering that included the Geologic and Mining Division, while the Metallurgy Division was established only in 1939. Today, the Departments of Geology, Mining and Geotechnology, Materials and Metallurgy are all part of the Faculty of Natural Sciences and Engineering, University of Ljubljana. Before World War II, the members of the Mining Section together with the Association of Yugoslav Mining and Metallurgy Engineers began to publish the summaries of their research and studies in their technical periodical Rudarski zbornik (Mining Proceedings). Three volumes of Rudarski zbornik (1937, 1938 and 1939) were published. The War interrupted the publication and it was not until 1952 that the first issue of the new journal Rudarsko-metalurški zbornik - RMZ (Mining and Metallurgy Quarterly) was published by the Division of Mining and Metallurgy, University of Ljubljana. Today, the journal is regularly published quarterly. RMZ - M&G is co-issued and co-financed by the Faculty of Natural Sciences and Engineering Ljubljana, the Institute for Mining, Geotechnology and Environment Ljubljana, and the Velenje Coal Mine. In addition, it is partly funded by the Ministry of Education, Science and Sport of Slovenia. During the meeting of the Advisory and the Editorial Board on May 22, 1998, Rudarsko-metalurški zbornik was renamed into "RMZ - Materials and Geoenvironment (RMZ - Materiali in Geookolje)" or shortly RMZ - M&G. RMZ - M&G is managed by an advisory and international editorial board and is exchanged with other world-known periodicals. All the papers submitted to the RMZ - M&G undergoes the course of the peer-review process. RMZ - M&G is the only scientific and professional periodical in Slovenia which has been published in the same form for 60 years. It incorporates the scientific and professional topics on geology, mining, geotechnology, materials and metallurgy. In the year 2013, the Editorial Board decided to modernize the journal's format. A wide range of topics on geosciences are welcome to be published in the RMZ - Materials and Geoenvironment. Research results in geology, hydrogeology, mining, geotechnology, materials, metallurgy, natural and anthropogenic pollution of environment, biogeochemistry are the proposed fields of work which the journal will handle. Že več kot 90 let je minilo od ustanovitve Univerze v Ljubljani leta 1919. Tehnične stroke so se združile v Tehniški visoki šoli, ki sta jo sestavljala oddelka za geologijo in rudarstvo, medtem ko je bil oddelek za metalurgijo ustanovljen leta 1939. Danes oddelki za geologijo, rudarstvo in geotehnologijo ter materiale in metalurgijo delujejo v sklopu Naravoslovnotehniške fakultete Univerze v Ljubljani. Pred 2. svetovno vojno so člani rudarske sekcije skupaj z Združenjem jugoslovanskih inženirjev rudarstva in metalurgije začeli izdajanje povzetkov njihovega raziskovalnega dela v Rudarskem zborniku. Izšli so trije letniki zbornika (1937, 1938 in 1939). Vojna je prekinila izdajanje zbornika vse do leta 1952, ko je izšel prvi letnik nove revije Rudarsko-metalurški zbornik - RMZ v izdaji odsekov za rudarstvo in metalurgijo Univerze v Ljubljani. Danes revija izhaja štirikrat letno. RMZ - M&G izdajajo in financirajo Naravoslovnotehniška fakulteta v Ljubljani, Inštitut za rudarstvo, geotehnologijo in okolje ter Premogovnik Velenje. Prav tako izdajo revije financira Ministrstvo za izobraževanje, znanost in šport. Na seji izdajateljskega sveta in uredniškega odbora je bilo 22. maja 1998 sklenjeno, da se Rudarsko-metalurški zbornik preimenuje v RMZ - Materiali in geookolje (RMZ -Materials and Geoenvironment) ali skrajšano RMZ - M&G. Revijo RMZ - M&G upravljata izdajateljski svet in mednarodni uredniški odbor. Revija je vključena v mednarodno izmenjavo svetovno znanih publikacij. Vsi članki so podvrženi recenzijskemu postopku. RMZ - M&G je edina strokovno-znanstvena revija v Sloveniji, ki izhaja v nespremenjeni obliki že 60 let. Združuje področja geologije, rudarstva, geotehnologije, materialov in metalurgije. Uredniški odbor je leta 2013 sklenil, da posodobi obliko revije. Za objavo v reviji RMZ - Materiali in geookolje so dobrodošli tudi prispevki s širokega področja geoznanosti, kot so: geologija, hidrologija, rudarstvo, geotehnologija, materiali, metalurgija, onesnaževanje okolja in biokemija. Glavni urednik Editor-in-Chief Original scientific paper Received: August 3, 2015 Accepted: September 2, 2015 Stochastically improved methodology for probability of success (POS) calculation in hydrocarbon systems Stohastično dopolnjena metodologija računanja verjetnosti uspeha (POS) v ogljikovodičnih sistemih Tomislav Malvić1, 2 *, Josipa Velić1 1INA Plc., Field Development Sector, Šubićeva 29, 10000 Zagreb, Croatia 2University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Pierottijeva 6, 10000 Zagreb, Croatia Corresponding author. E-mail: tomislav.malvic@zg.t-com.hr Abstract Geological risk of new hydrocarbon reserves discovering is usually calculated on deterministical or expert-opinion way, and expressed as 'Probability Of Success' (abbr. POS). In both approaches are included selections of single probability values for each geological event organised into geological categories that define hydrocarbon system. Here is described a hybrid, i.e. stochastical, model based on the deterministical approach. Here was given example from the Croatian part of the Pannonian Basin System (abbr. CPBS), improved with stochastically estimated subcategory for porosity mapped in the Stari Gradac-Barcs Nygat Field (Drava Depression). Furthermore, there is theoretically explained how such approach could be applied for two other subcategories - quality of cap rocks and hydrocarbon shows. Presented methodology could be advantageous in clastic hydrocarbon system evaluation. Key words: geological risk, determinism, stochastics, Neogene, Northern Croatia Izvleček Geološko tveganje odkritja novih zalog ogljikovodikov navadno računajo deterministično ali po metodi ekspertnih mnenj in ga izražajo z »verjetnostjo uspeha« (POS, Probability of Success ). Obe metodi temeljita na vrednostih verjetnosti posamičnih geoloških dogodkov, urejenih po geoloških kategorijah, ki opredeljujejo ogljikovodični sistem. Tu je opisan hibridni, tj. stoha-stični model, ki temelji na determinističnem načinu. Obravnavani primer je iz hrvaškega dela sistema Panonske kadunje (CPBS, Croatian part of the Pannonian Basin System), ki je dopolnjen s stohastično ocenjeno podkategorijo poroznosti, kartirano v polju Stari Gra-dac-Barcs Nygat (v Dravski kadunji). Sledi teoretska razlaga možnosti uporabe takega načina z nadaljnjima dvema podkategorijama - kakovostjo krovnih kamnin in ogljikovodičnih pojavov. Prikazana metodologija utegne biti učinkovita pri ocenjevanju klastičnih ogljikovo-dičnih sistemov. Ključne besede: geološko tveganje, determinizem, sto-chastičnost, neogen, severna Hrvaška Introduction Calculation of geological risk is a well-established tool for estimation of possible hydrocarbon reservoir in plays or prospects. Such calculations, in Croatia, are well described in the Sava and Drava Depressions [1-4]. The term 'play' in those papers is generally defined as a stratigraphical unit in the range of chronostrati-graphic stage or sub-stage where hydrocarbon production already exists. The 'prospect' is a vertical surface projection of potential reservoir lateral borders. Such definition has been derived from Rose [5] or White [6] where 'play' is generally defined as an operational unit characterised by several prospects and/or fields and 'prospect' is an exploration (economic) unit. In general, any potential hydrocarbon system can be evaluated with Probability of success (abbr. POS) calculation. Mathematically, calculation of POS is a simple multiplication of several, in most cases five, independent geological category probabilities. Of course, there are geological relations among some of them, but it is using this tool impossible mathematically expressed on any useful way. Each category is defined with several geological events, and each also has its own probability. Category probability is simple multiplication of selected event probability values, defined as discrete values in range 0-1. They are often listed in POS probability tables, based upon previous experience and expert knowledge from analysed subsurface. Such a table (Figure 1), defined through decades of research for the Croatian part of the Pannonian Basin System (abbr. CPBS), had been a source of detail probability values defined and applied in in the Bjelovar Subdepression as part of the Drava Depression. Sometimes such values remain as an TRAP RESERVOIR SOURCE ROCKS MIGRATION 1 HC PRESERVATION | Structural Reservoir type Source facies HC shows Reservoir pressure Anticline and buried hill linked to basement 1.00 Sandstone clean and laterally extended; Basement granite, geiss, gabbro; Dolomites and Algae reefs (secondary porosity) 1.00 Kerogen type I and/or II 1.00 Production of hydrocarbons 1.00 Higher than hydrostatic 1.00 Faulted anticline 0.75 Sabdstones, rich in silt and clay; Basement with secondary porosity, limited extending; Algae reefs, filled with skeletal debris, mud and marine cements 0.75 Kerogen type III 0.75 Hydrocarbons in traces; New gas detected >10 % 0.75 Approximately hydrostatic 0.75 Structural nose closed by fault 0.50 Sandstone including significant portion of silt/clay particles, limited extending; 0.50 Favourable palaeo-facies organic matter sedimentation 0.50 Oil determined in cores (luminescent analysis, core tests) 0.50 Lower than hydrostatic 0.50 Any "positive" faulted structure, margins are not firmly defined 0.25 Basement rocks, including low secondary porosity and limited extending 0.25 Regionally known source rock facies, but not proven at observed locality 0.25 Oil determined in traces (lumin, anal., core tests) 0.25 0.25 Undefined structural framework 0.05 Undefined reservoir type 0.05 Undefined source rock type 0.05 Hydrocarbon are not observed 0.05 0.05 Stratigraphic or combined Porosity features Maturity Position of trap Formation water Algae reef form 1.00 Primary porosity >15 %; Secondary porosity >5 % 1.00 Sediments are in catagenesis phase ("oil" or "wet" gas- 1.00 Trap is located in proven migration distance 1.00 Still aquifer of field-waters 1.00 Sandstones, pinched out 0.75 Primary porosity 5-15 %; Secondary porosity 1-5 % 0.75 Sediments are in metagenesis phase 0.75 Trap is located between two source rocks depocentres 0.75 Active aquifer of field-waters 0.75 Sediments changed by diagenesis 0.50 Primary porosity <10 %; Permeability <1x10**(-3) micrometer**2 0.50 Sediments are in early catagenesis phase 0.50 Short migation pathway (<=10 km) 0.50 Infiltrated aquifer from adjacent formations 0.50 Abrupt changes of petrophysical properties (caly, different facies) 0.25 Secondary porosity <1 % 0.25 Sediments are in late diagenesis phase 0.25 Long migration pathway (>10 km) 0.25 Infiltrated aquifer from surface 0.25 Undefined stratigraphic framework 0.05 Undefined porosity values 0.05 Undefined maturity level 0.05 Undefined source rocks 0.05 0.05 Quality of cap rock Data sources Timing Regional proven cap rock (seals, isolator) 1.00 1.00 Geochemical analysis on cores and fluids 1.00 Trap is older than matured source rocks 1.00 1.00 Rocks without reservoir properties 0.75 0.75 Analogy with close located geochemical analyses 0.75 Trap is younger than matured source rocks 0.75 0.75 Rocks permeable for gas (gas leakage) 0.50 0.50 Thermal modeling and calculation (e.g. Lopatin, Waples etc.) 0.50 Relation between trap and source rocks is unknown 0.50 0.50 Permeable rocks with locally higher silt/clay content 0.25 0.25 Thermal modeling at just a few locations 0.25 0.25 0.25 Undefined cap rock 0.05 0.05 Undefined data sources 0.05 0.05 0.05 Figure 1: Example of relevant database prepared for the Bjelovar Subdepression 'after2 internal document, but only if published [eg 2 3] they make possible further independent evaluation of local or regional petroleum systems. Oppositely, such general tables, which can be applied as a rule of thumb, are missed in case of expert opinion applied for each particular well, exploration or development plan (Figure 2). In such case, single expert or team are completely responsible for given category values. Consequently, such process is subdued to "heavy" benchmarking, i.e. corrections are done with each new dataset (especially from wells). This methodology is not discussed here. However, it is obvious that, using deterministic approach, at least several geological events (Figure 2) can be estimated from the range, i.e. from interval defined with values, number of data and, sometimes, measurement error. Moreover, in the case of low number of inputs, the Monte Carlo sampling can be applied for generation of artificial data, but it needs to be clearly stated in statistical results. However, the key question is "can any probability value for each geological event be considered certain or not". If there is a measurable uncertainty (Figure 2), resulting in non-representative mean or variance, but the minimum and max- imum could be approximated, the stochastics can be successfully applied, e.g., using 2nd introduction of uncertainty in cell-value estimations with sequential Gaussian simulations. Such application of stochastics and results are shown, for the CPBS, in estimation of the porosity, thickness and depth of hydrocarbon reservoirs [eg 7-9]. Similar approach obviously can be regularly applied for estimation of several events in POS calculation and eventually set up as standard part of that method. Selection of stochastically mapped porosity in POS calculation The hydrocarbon plays or prospects could be deterministically analysed by several, mathematically independent, geological categories. The most common are: (1) structures, (2) reservoirs, (3) migration, (4) source rocks and (5) preservation of hydrocarbons [eg 2 3 6 10]. The values of events in the most category values can be evaluated from data collected from well files, logs, seismic, cores, descriptive geological interpretations or the comprehensive regional papers [eg 11-13]. Based upon those data, Analysed here DETERMINISTICAL SYSTEM Purely deterministical system based onto large number of discrete values set for analysed geological system. Values are considered as constants, categories are independent. Advantages The procedure is clear and can be transparently report to anyone. Disadvantages Ask for large knowledge about analysed subsurface volume, often collected after decades of exploration. Not analysed here HUMAN SUPERVISED BENCHMARKING SYSTEM The humans use some discrete values based on own or community experience. The POS could be calculated from independent or depend events. Advantages Can be applied for ever subsurface volume, even poorly explored. Analogy can be applied. Disadvantages Completely based on expert knowledge, hardly can be independently re-checked. Methodology can be mathematically improved, respecting geological possibilities «Interval of allowed estimation uncertainty» can easily be applied in: (a) sequential mapping of some (sub)categories, (b) establishing interval of values from available measurements Figure 2: Deterministical vs. human dominant benchmarking in evaluation of hydrocarbon systems. a value from the probability table can be easily selected, if such exists for the explored area (like Figure 1) or even from analogy based on regional geological models, especially deposi-tional and tectonic data [eg.' 11]. In any case, POS table makes possible to calculate such value for any play or prospect in the area where it is defined by Equation 1: POS = p (structures) x p (reservoir) x p (migration) X p (source rocks) x p (preservation) (1) Where are: POS - probability value of Probability of Success for analysed hydrocarbon system, p - probability value of each considered geological category. All geological events, subcategories, categories and POS are defined with numerical values. For the part of them inputs (laboratory measurements, loggings tools ...) strictly define the results (like kerogen type, quantity of hydrocarbons during drilling) and probability can be selected without uncertainties. However, some subcategories like 'Porosity features' (in the category 'Reservoir'), 'Quality of cap rocks' ('Trap'], and 'HC shows' ('Migration') can be calculated from cores, logs and diagrams, but very often as approximations. It means they includes uncertainties, but if lithology is well-known the minimum and maximum values (e.g., for porosity) could be clearly established. The methodology had been tested with porosity maps taken from the Badenian gas-condensate reservoir in the Stari Gradac-Barcs Nyu-gat Field [14]. The reservoir is of massive type, trapped with combined structural-stratigraph-ic closure, with very complex lithology divided in four lithofacies (but single hydrodynamic unit). Porosity is geostatistically mapped in the youngest lithofacies of the Badenian clastites. The porosity distribution corresponds with structural strike NW-SE [15], and maps had been calculated using 100 realizations of sequential Gaussian simulations. It means that each cell on the map is defined with minimum and maximum values (realization), as well as 98 others between them. All of them, as equally probable, had been summed and averaged. So the minimum (3.1 %), median (3.2 %) and maximum (3.53 %) average reservoir porosities are calculated, what was base for consequently calculation of three solutions for 'Original Gas In Place' (abbr. OGIP) volume [16]. Trap Structural stratigraphie or combined Reservoir Source rocks Reservoir type Source facies Porosity features Maturity Migration Preservation of HC Ut shows Reservoir pressure Position of trap Formation water Quality of cap rock Data sources Timing Tr)[b Gmalo^cmt r-iif-cgcirrfls Quality ■of ^p CccH- tfrsf ccnjId Лг indirètti? mtuii-iitaii Лас1яЛЛсяПу Stipulai Gcoi&pitàt subcategories CSfJ'JTmtC 70 %). The melanosomes contain varying amount of ferromagnesian minerals like platy biotite, prismatic hornblendes and equant pyroxene. Melanosomes are also identified as xenoliths. The presence of pyroxene confers a greenish tint on the rock body. The composite fabrics of paleosomes and neosomes are folded on mesoscopic scale. The paleosomes and leucosomes are concurrently folded and terminate abruptly into what appears as an enclave or tight isoclinal fold (Figure 2). The trends of the fold axis are mostly east- west. Lineation plunges usually to the north, reflecting ductile deformation. Deformations are mainly ductile. Fragments of enclaves or raft structure (competent materials) are enveloped within less competent components. The enclaves are mainly mafic subordinately felsic. These enclaves are of various shapes and sizes. Large number of shear planes was recognized in the study area, shearing was identified due to fabrics of the tectonically deformed rocks. Shearing had led to formation of various structural features like reorientation due to rotation, boudins and lenses (Figure 2). Enclaves are rock fragments that resisted migmatisation (resisters) or residual materials from which mobile materials have been extracted [5, 6]. Materials and Methods Geological mapping of Awo area was conducted on a scale of 1 : 50 000. Particular attention was taken for the location, physical characteristics, mineral constituents, structural elements and associated rocks of the migmatite gneiss. Sampling was done to preserve various structures within the migmatite gneiss for future studies. A few samples were collected from each rock body for geochemical analysis. Various field measurements were used during the mapping. Global Positioning System (GPS) was used for geographical positioning with respect to various outcrops available in the study area. Measurement of strike, dip, plunge of structures such as foliation, lineation and fold axis were made. Field descriptions and observation were adequately recorded in a field notebook. Samples collected were properly labeled and stored prior to analyses. Representative rock samples were pulverized at Geochemistry Laboratory, Department of Geology of the University of Ibadan and analyzed at ACME Laboratory, Ontario, Canada using X-Ray Fluorescence (XRF) methods. Geochemical data were processed using Petrographic software package for different geochemical variation and discrimination diagrams. Table 1: Chemical composition of the Migmatite gneiss of Awo NEOSOME PALEOSOME Major element concentration in mass fractions, w/% Analyte RS1 RS2 RS3 RS4 RS5 Mean Range RS6 RS7 RS8 RS9 Mean Range SiO2 44.5 55.5 58.7 61.5 61.5 56.34 61.5-44.5 65.1 63.8 65.3 74.2 67.1 74.2-63.8 Al2O3 12.54 14.77 14.93 14.49 15.16 14.38 15.16-12.54 14.96 14.39 14.43 15.50 14.82 15.50-14.39 Fe2°3 18.10 8.47 11.29 5.72 9.34 10.60 18.10-5.72 6.22 7.80 7.34 0.39 5.44 7.80-0.39 CaO 6.31 7.36 2.26 4.67 2.50 4.62 7.36-2.50 3.09 2.92 2.00 0.43 2.11 3.09-0.43 MgO 7.65 6.63 3.94 5.40 3.35 5.40 7.65-3.35 2.23 2.86 2.55 0.08 1.93 2.86-0.08 N^O 0.52 2.69 2.35 2.95 2.82 2.27 2.95-0.52 3.46 2.94 3.42 7.14 4.24 7.14-2.94 K2O 5.32 2.20 4.15 3.15 3.66 3.70 5.32-2.20 2.57 3.03 3.15 1.90 2.66 3.15-1.90 MnO 0.39 0.17 0.21 0.16 0.15 0.22 0.39-0.15 0.12 0.15 0.15 0.11 0.13 0.15-0.11 TiO2 2.43 2.08 1.77 0.74 1.32 1.47 2.43-0.74 1.00 1.30 1.22 0.04 0.89 1.30-0.04 P2O5 0.58 0.49 0.06 0.62 0.04 0.36 0.62-0.04 0.11 0.13 0.07 0.20 0.13 0.20-0.07 LOI 1.67 0.37 0.73 0.54 0.64 0.79 1.67-0.37 0.47 0.56 0.49 0.52 0.51 0.56-0.47 Total % 100.01 99.73 100.39 99.94 100.48 99.33 99.88 100.12 100.51 NEOSOME PALEOSOME Trace element concentration (x 10-6) Analyte RS1 RS2 RS3 RS4 RS5 Mean Range RS6 RS7 RS8 RS9 Mean Range Cu 20 10 70 10 10 24 70-10 20 10 10 10 13 20-10 Ni 270 110 100 40 90 122 270-40 10 40 30 10 11 40-10 Pb 10 10 10 10 10 10 10 10 10 10 10 10 10 Zn 250 110 160 120 110 150 250-110 10 110 110 40 68 110-10 Zr 161 186 425 189 231 238 231-161 251 307 367 24 242 367-24 Ba 706 478 992 871 638 737 992-478 647 891 667 42 562 891-42 Be 2 36 7 2 51 20 51-2 4 2 4 6 4 6-2 Co 38 32 32 27 23 30 38-23 18 18 20 1 14 20-1 Cs 4 20 4 3 30 12 30-3 2 2 3 4 3 4-2 Ga 26 19 21 21 20 54 54-19 18 20 19 22 20 22-18 Rb 187 166 159 137 245 179 245-137 94 116 141 158 127 158-94 Sn 6 4 1 2 3 3 6-1 1 1 6 11 5 11-1 Sr 68 277 297 393 356 267 356-68 303 299 247 10 215 303-10 V 261 182 203 188 78 182 261-78 100 135 125 10 93 135-101 Hf 5 5 12 5 6 7 12-5 8 11 10 1 8 11-1 Nb 40 30 30 26 37 31 40-26 15 16 26 20 19 20-15 Ta 2 6 1 1 11 4 11-1 1 1 1 1 1 1 Th 2 14 32 31 20 20 32-2 25 29 16 2 18 29-2 U 2 6 2 1 10 4 10-1 1 1 2 5 2 5-1 W 1 3 2 2 5 3 5-1 2 1 1 4 2 4-1 Y 62 30 24 20 24 32 62-20 23 25 13 6 17 25-6 Figure 2: Migmatite gneiss showing various structures: top left - basic dyke; top right - sheared boudins; middle left - rotated and folded metabasic rocks; middle right - symmetrical tail of leucosome around an enclave of melanosome; bottom left - randomly oriented raft structure of basic dykes embedded in matrix of leucosome; bottom right - tight folding of foliated paleosome, leucosome and melanosome. Results and Discussion Major Element Geochemistry Nine representative samples of the paleosomes and neosomes were selected to determine their major, trace and rare earth elements geochemistry. Five of the samples were taken from paleosomes and four from neosomes (Table 1). The xenolith expectedly has very low concentration of Na2O (w = 0.52 %), and much higher concentrations of K2O (w = 5.32 %) and a proportionately high concentration of Fe2O3 (w = 18.10 %) and MgO (w = 7.65 %) due to its mafic composition (Table 1). The paleosomes and neosomes of the migmatite gneisses are compositionally different in their mean values as revealed by major oxide data presented in Table 1.The lowest mean value of SiO2 is w = 44.5 % which indicates the mafic nature of the paleosomes while the highest mean value of SiO2 is w = 74.2 % which as well reveal the felsic nature of the neosomes. Low range values of oxides such as Na2O (w = 2.95-0.52 %) and high range values of Fe2O3 and MgO (w = 18.10-5.72 % and w = 7.65-3.35 %) further affirm the mafic composition of the paleosomes. The overall trend for all major elements suggests that the paleosomes evolved from parent material which is intermediate between felsic and mafic sources. This is evident from the moderately high concentration of SiO2 in the range of w = 61.5-44.5 % while a range value of w = 74.2-63.8 % for neosomes clearly indicates its felsic precursor. High contents of Fe2O3 (w = 18.10-5.72 %) for paleosomes attest the basic nature of the parent materials, while low Fe content (w = 7.800.39 %) in neosome indicates its felsic parentage. The mean values of Na2O and K2O (Table 1) for the paleosomes and neosomes reflect the abundance of K-rich rock forming silicates like biotite and microcline [7]. The paleosome and neosome show slight variation in their sources. The paleosomes are derived from diorite and syenodiorite sources whereas the neosomes are mostly derived from quartz diorite and granite sources (Figure 3). The AFM diagrams [9, io] were used to determine whether the rock samples are derived from tholeiitic or calc-al-kaline rock suite, the major element data were plotted on triangular diagram comprising of A (Na2O + K2O), F (FeO + Fe2O3) and M (MgO). The plot falls within calc- alkaline rock suite which is rich in Na2O, K2O and total Fe but low in MgO (Figure 3). The AFM diagrams were also employed to investigate the enrichments of the paleosomes and neosomes in Na2O, K2O, MgO and total Fe. The paleosomes are moderately enriched in MgO and total Fe while the neosomes are highly enriched in Na2O and K2O with low amount of total Fe (Figure 3). It is further confirmed by the plot of SiO2 versus Na2O + K2O [8] which revealed that the migmatite gneiss originates from dioritic rocks (Figure 3). SiO2 was plotted against K2O adopting the model of Pec-cerillo and Taylor [13] to further determine if the rock series is high or medium calc-alkaline (Figure 3). In term of tectonic setting, following the model of Pearce et al [17] where Rb was plotted against Y + Nb, the neosome plots in the field of Volcanic Arc Granite while the paleosome plots in Within Plate Granite (Figure 3). Both components are thus product of post-col-lisional tectonic setting. Most of the values plot within field of high-K calc- alkaline series. Furthermore, all the major oxides were plotted against SiO2 in Harker's diagram (Figure 4) because SiO2 is regarded as fractionation index for the evolution of magma and the most abundant oxide in igneous rocks that exhibit a wide variation in composition [11]. Al2O3 and Na2O are positively correlated with SiO2 which is an indication of possible separation of felsic minerals like sodic plagioclase during fractional crystallization [12]. Fe2O3, CaO, K2O and MgO versus SiO2 were negatively correlated and indicate a separation of ferromagnesian minerals during crystallization (Figure 4). Various models were used to determine the ancestry of the migmatite gneiss. Awo migmatite gneiss on the Na2O/Al2O3 vs K2O/Al2O3 plot was used to discriminate between igneous and sed-imentary/metasedimentary rocks [14]. Approximately 90 % of the plots fell within sedimenta-ry/metasedimentary field (Figure 5). Similarly, the K2O vs Na2O plot [8] showed an overwhelming 90 % of the values plotting within eugeo-synclinal sandstones field (Figure 5). Furthermore, in the TiO2 vs SiO2 diagram [16], the plot fell within sedimentary field which suggests that the protolith of the migmatite gneiss has been grossly affected by crustal contamination (Figure 5). Trace and Rare Earth Elements Geochemistry Trace element concentrations of the paleosome and neosome are presented in Table l.The concentrations of Large Ion Lithophile Elements (LILE] such as Ba, Rb and Sr for paleosomes and neosomes are enriched, but the mean values are slightly higher in paleosome than neosome (Table 1). The concentrations of High Field Strength Elements (HFSE] like Ta, Nb and Hf are generally depleted; neosomes are more depleted in HFSE than paleosomes. However Zr is moderately enriched compared to other HFSE (Table 1). For trace elements, high content of Ba with mean values of 737 x 10-6 and 562 x 10-6 for paleosome and neosome respectively (Table 1] are conspicuously discernible which indicates its concentration in felsic minerals. This attests to granitic origin of the rock samples. The assertion is further corroborated by moderate amount of Rb (179 x 10-6 and 127 x 10-6 ] and Zr (238 x 10-6 and 242 x 10-6) for paleosomes and neosomes respectively which are concentrated in rocks of acidic or intermediate composition. The LILE such as Ba, Rb and Sr generally exhibit positive anomaly, while HFSE such as Ta, Nb, Hf and Zr display weak anomaly (Figure 6]. 35 40 45 50 55 65 70 75 X= SÌ02 Y= (No20+K20) 10"0 10-1 10"2 10"3 10"4 Figure 3: Top left - AFM diagrams (after Irvine and Baragar[Ю]); middle left - (after Kuno[9]); top right - Plot of Na2O Kp versus SiO2 (after Cox et al[8]); middle right - Kp versus Sp2plot (after Peccerillo and Taylor n3]); bottom - Rb versus Y+Nb tectonic discrimination diagram (after Pearce et alП7!). Figure 4: Harker's variation plot of SiO2 versus other major elements 0.4 Nn..ü/Л .О KEY X Paleosome Igneous • Neosome * .... • X ■..... x • • Sedimentary and Metasedimentary « 0.2KjO/AI/J3 0.3 0.4 0.5 Figure 5: Top - TiO2 versus SiO2 plot (after Tarney"6'); middle - K2O vs Na2O plot (afterMiddlemost1151); bottom - Na2O/Al2O3 versus K2O/Al2O3 diagram (after Garrels and Mackenzie1141). Rb Ea Th U K Nb La Ce Sr Nd P Hl Zi Sm Ti Tb V Tm Vb Hb Ba Th U V. Nb La Cs S, Nd P HI Z, Sm Ti Th Y Tu, Yh Figure 6: Left - Mantle normalized pattern of trace elements for Paleosome and neosome (after Wood et al"81); right - Chondrite normalized pattern of rare earth elements for paleosomes and neosomes after Haskin et al1'91). The enrichment in LILE and depletion in HFSE reflect geotectonic setting from which the rocks originated. The setting suggests the rocks to evolve in a process of subduction. REE concentrations of the paleosomes and neosomes as presented in Table 1 reveal strong positive anomaly for LREE such as La, Ce, Pr and Nd while HREE like Ho, Er, Tm, Yb, and Lu show weak anomaly. Source materials of the migma-tite gneiss can be inferred from trace and rare earth element patterns [12]. The moderately enriched LREE and weakly negative Eu anomaly possibly suggest the melt to have been derived from rocks of intermediate composition like diorite and quartz diorite (Figures 5 and 6]. Conclusion The study area occurs within metamorphic terrane of the south western basement complex of Nigeria. Formation of different rock types around the area is probably connected to post-collisional events that influenced the structural and textural features of the various geological units. The available geochemical data from the study area suggest the paleosomes and neosomes to be mostly of sedimentary parentage with minor input from igneous protolith (Figure 5]. The paleosome and neosome bear compositional similarities. However, minor pe-trological differences exist between each component. The differences are associated with the composition of their sources and crustal contamination during the transportation of the melted materials. The migmatite gneiss is derived from rocks of dioritic composition belonging to calc-alkaline series. Negative correlation between SiO2 and major elements like Fe2O3, CaO, K2O and MgO indicate a pronounced effect of fractional crystallization during the formation of the dioritic rocks. Large Ion Litho-phile Elements (LILE] such as Ba, Rb and Sr generally exhibit positive anomaly while High Field Strength Elements (HFSE] notably Ta, Nb, Hf and Zr display negative anomaly. The REE geochemistry revealed strong positive anomaly for LREE (La, Ce, Pr and Nd] while HREE (Ho, Er, Tm, Yb and Lu] are weakly anomalous. Evidence from geochemical data coupled with pat- terns of major, trace elements and rare earth elements revealed that the paleosomes and neosomes have common magmatic and geotec-tonic source. References [1] Allen, T. T. (1992): Migmatite Systematics and Geology Carter Dome - Wild River Region, White Mountains, New Hampshire. Ph. D. Thesis, Dartmouth College. [2] Sawyer, E. W. (2008) Identifying parts of Migma-tites in the Field. In Sawyer E.W and Brown M (eds) Working with Migmatites. Mineralogical Association of Canada, Short Course; 38, pp. 29-36. [3] Sawyer, E. W., Cesare, B., Brown, M. (2011): When the Continental Crust Melts. Mineralogical Society of America; 7 (4), pp. 229-234. [4] Odeyemi, I. B., Rahaman, M. A. (1992): The Petrology of a Composite Syenite dyke in Igarra, Southwestern Nigeria. Journal of Mining and Geology; 28 (2), pp. 255-264. [5] Shelley, D. (1997): Igneous and Metamorphic rocks under microscope. Chapman & Hall, pp.1-445. [6] Pereira, M. F., Silva, J. B. (2002): The Geometry and Kinematics of Enclaves in sheared Migmatites from the Evora Massif, Ossa-Morena zone (Portugal). Geogaceta; 31 pp. 193-196. [7] Oyinloye A. O. (2011): Geology and Geotectonic Setting of the Basement Complex Rocks in Southwestern Nigeria: Implications on Provenance and Evolution, Earth and Environmental Sciences, Dr Imran Ahmad Dar (Ed), pp. 97-118. [8] Cox, K. G., Bell, J. D., Pankhurst, R. J. (1979): The Interpretation of Igneous rocks. London, George Allen and Unwin, 450 p. [9] Kuno, H. (1968): Differentiation of basalt magmas. In: Hess H. H. and Poldervaart A. (eds), Basalts: The Poldervaart treatise on rocks of basaltic composition; 2, Interscience, New York, pp. 623-688. [10] Irvine, T. N., Baragar, W. R. A. (1971): A guide to the chemical classification of the common volcanic rocks. Journal of Petrology; 17, pp. 589-637. [11] Wilson, M. (1989): Igneous Petrogenesis. A Global Tectonic Approach, Unwin Hyman, London, 466 p. [12] Maulana, A, Watanabe, K, Imai, A., Yonezu, K. (2012): Petrology and Geochemistry of Granitic Rocks in South Sulawesi, Indonesia: Implication for Origin of Magma and Geodynamic Setting. World Academy of Science, Engineering and Technology; 61, pp. 8-13. [13] Peccerillo, A., Taylor, S. R. (1976): Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Contrib. Mineral. Petrol.; pp. 63-81. [14] Garrels, R. M., Mackenzie, F. T. (1971): Evolution of sedimentary rocks. W. W. Norton & Co. Inc. New York, 394 p. [15] Middlemost, E. V. (1960): Chemical composition of sandstone. Bulletin Geological Society of America; 71, pp. 1011-1026. [16] Tarney, J. (1977): Petrology, mineralogy and geochemistry of the Falkland Plateau basement rocks, site 330, deep sea drilling project, Initial Report; 36, pp. 893-921. [17] Pearce, J. A., Harris, N. B. W., Tindle, A. G. (1984): Trace element discrimination diagrams for the tectonic classification of granitic rocks. Journal of Petrology; 25, pp. 956-983. [18] Wood, D. A., Joron, J. L., Treuil, M., Norry, M., Tarney, J. (1979): Elemental and Sr isotope variations in basic lavas from Iceland and the surrounding ocean floor. Contrib. Mineral. Petrol.; 70, pp. 319-329. [19] Haskin, L. A., Haskin, M. A., Frey, F. A., Wildman, T. R. (1968): Relative and Absolute terrestrial abundances of rare earths. In: Ahrens L.H. (ed) Origin and Distribution ofthe elements; 1, Pergamon, Oxford, pp. 889-911. Original scientific paper Received: August 13, 2015 Accepted: September 24, 2015 Data preparation for groundwater modelling - Ljubljansko polje aquifer system Priprava podatkov za modeliranje podzemne vode -vodonosni sistem Ljubljansko polje Janja Vrzel1- 2 *, Nives Ogrinc2- 3, Goran Vižintin4 Ecological Engineering Institute, Ljubljanska 9, 2000 Maribor, Slovenia international Postgraduate School Jožef Stefan, Jamova 39, 1000 Ljubljana, Slovenia 3Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia 4University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, 1000 Ljubljana, Slovenia Corresponding author. E-mail: janja.vrzel@iei.si Abstract The paper presents data preparation for groundwater modelling of Ljubljansko polje aquifer system in central part of Slovenia. Data preparation is part of the conceptualisation, which is the first step for developing a regional steady state model. This model will provide a framework for the development of transient groundwater flow model for the whole Ljubljansko polje aquifer system. The FEFLOW software is used for the visualization of the groundwater flow model of the Ljubljansko polje aquifer system and its geometry is based on the geological composition and hydrological characteristics of the studied area. Already known fact that too precise model geometry leads to the instability of the model was proved in ours study case, therefore many deliberate and rational decisions should be made during the conceptualisation. The model will extend our knowledge about interactions between surface and groundwater. Key words: FEFLOW, GIS, modelling, Ljubljansko polje aquifer system Izvleček V prispevku je opisana priprava podatkov za modeliranje vodonosnega sistema Ljubljansko polje, ki se nahaja v osrednji Sloveniji. Priprava podatkov je del koncep-tualizacije obravnavanega območja - prvega koraka v pripravi regionalnega stacionarnega modela. Le-ta pa bo pozneje nadgrajen v nestacionarni hidrodinamski model vodonosnega sistema Ljubljansko polje. Model pripravljamo v računalniškem programu FEFLOW, definicija njegove geometrije pa temelji na geološki sestavi in hidroloških lastnostih vodonosnika. Potrdili smo že znano dejstvo, da preveč natančna geometrija modela povzroča njegovo nestabilnost pri umerjanju, zato je potrebno med konceptualizacije sprejeti dobro premišljene odločitve, s katerimi se model poenostavi do takšne mere, da še lahko pričakujemo zadovoljive rezultate. Nastajajoč model bo razširil naše znanje o interakciji med površinsko in podzemno vodo. Ključne besede: FEFLOW, GIS, modeliranje, vodonosni sistem Ljubljansko polje Introduction Hydrological cycle is one of the most important cycles for people and their environment, therefore a lot of attention, efforts and money were directed to control its processes through the history. Special attention should be paid to groundwater research, where it is important to know its sources, infiltration areas, its dynamics and vulnerability to possible contamination from industrial and agricultural activities, and to assure its sustainable development for future generations. Nowadays, new technologies involving different models enable us to better understand rather complex processes of the hydrologic cycle [1]. The model is defined as a simplified representation of a complex natural system with three different types of applications: (1) predictive, used as a framework for prediction of future conditions, (2) interpretative, used for studying system dynamics or organizing data, and (3) generic, used to analyse the hypothetical hydrogeologic systems [2]. A regional steady state model for the whole Ljubljansko polje aquifer system is under preparation, which is the main drinking water source for Slovenian capital city Ljubljana and its surroundings. The aquifer has also economic importance, since this aquifer is also an invaluable water resource for the Union brewery (Pivovarna Union, d. d.) located within a highly urbanized and industrialized area near the centre of Ljubljana. The groundwater model will be extended into a transient transport model describing the transport of stable isotopes of O and H and 3H activity. The transport of dissolved species in groundwater systems facilitate to assess potential hazards to the public, when contaminants are used as transport material. The vulnerability of aquifer to environmentally harmful substances was observed in previous investigations: higher concentrations of herbicide diklobenil were detected in drinking water in 2001 due to maintenance of cemeteries; and high concentrations of atrazine could still be detected in drinking water in 2003 due to intensive agriculture [3, 4]. Few models of groundwater flow in Ljubljansko polje aquifer system were already developed in the past [5-7]. The aim of our work is to upgrade the existing models of Ljubljansko polje system with finite elements numerical model able to represent Sava river with higher accuracy than any other numerical model build until now. Numerical modelling of a physical system requires very well understanding of the system behaviours. The present work is motivated by the collection and processing of huge required data and the necessity to generate a complete DTM (Digital Terrain Model) of the entire computational domain, including the wetted region of the Sava river channel. The reason for it is in the great influence of the Sava on the elevation of the water table in the Ljubljansko polje aquifer system with intergranular porosity promoting the exchange between groundwater and Sava through the stream bed. Because of the high resolution of the Sava's bed geometry treatment in the groundwater model more stable model is expect during the calibration. Background At the Ljubljansko polje aquifer system (Figure 1) extensive investigation has been conducted in the last fifty years [8-10], therefore many geological and hydrological data are available for the formulation of a good conceptual model. Mathematical model simulates a natural system indirectly using a set of governing differential equations that describe physical processes occurring in the system, and numerical methods yield approximate solutions to the governing equation through the discretization of space and time [2, 11]. Many software were written to solve the governing equations for the different spatial, geological and hydrological conditions, which are based on two numerical techniques usually: the finite difference method (FDM), e.g. MODFLOW, and finite element method (FEM), e.g. FEFLOW. The FDM approximates differential equations by a differential approach, while FEM approximates differential equations by an integral approach [12]. The FEM is more appropriate choice when a subject of a research is a calculation of a precise water table elevation. On the other hand, it is better to use FDM when a calculation of a precise groundwater flux is performed. In our study the finite element flow simulation system FEFLOW® v6.1 from MIKE Powered by Danish Hydraulic Institute (DHI) was used, which enables to use stable isotopes as conservative transport materials. FEFLOW is a software package for three dimensional (3D) visualization of groundwater flow, mass transfer and heat transport in porous media. [14] 3D FEM for fluid flow and solute transport was developed by Huyakorn and Wadssworth in 1985 [13], while it is based on the equations for conservation of mass, Darcy's law for the anisotropic medium and the time-dependent species transport equation [14, 15]. The FEFLOW has the following advantages: (1) an ability to treat irregular shapes of a complex model boundary; (2) to refine the density of the mesh around features (e.g. wells, rivers, border, etc); (3) to simulate a groundwater age and transport of stable O and H isotopes [14]. Numerical models are used in parallel with development of powerful and affordable computer systems. In our case a 64-bit workstation under Windows 7 with CPU INTEL Core i7 and graphics ATI FirePro W7000 was used as a platform. The coefficients of the governing equations are the parameters that described the properties, boundaries, and stress of the system [11]. The choice of parameters is known as parameterisation, which is generally the most time-consuming procedure during modelling. The following data were obtained from different institutions/companies: (1) the counter map of the hardpan depth from VO-KA; (2) depths of piezometric groundwater table and groundwater abstractions from 48 and 35 wells, respectively from the VO-KA and Pivovarna Union, d. d, brewery; (3) isotopic analyses from the Jožef Stefan Institute. The ArcMap and AutoCAD Map were used for data processing before using FEFLOW. All three software FEFLOW, ArcMap and AutoCAD Map are fully integrated allowing quite easy transfer of the data between them. ArcMap and AutoCAD Map are geographic information systems (GISs), which are used for the management, analysis, and display of geographic information. GIS supports several views for working with geo- graphic information: (1) the geodatabase view, (2) the geovisualization view, (3) the geoprocessing view [15]. Further, a coordinate system is extremely important when we are dealing with geographic information. It is recommended to define it already in the GIS. Our model is prepared in D48/GK coordinate system. However, the replacement of the current coordinate system (D48/GK) with the European Spatial Reference System (ESRS) is in progress in Slovenia. Its horizontal direction is defined with the European Terrestrial Reference System (ETRS89/TM) [16]. Therefore, an extremely caution is required, while using GIS data since they are archived in different coordinate systems. The direction of groundwater flow within the Ljubljansko polje aquifer system is toward southeast in general. However, groundwater mining has a large influence on the hydrody-namic in the aquifer [17]. Ljubljansko polje aquifer system recharges mainly through infiltration of precipitation and river water. A smaller proportion of groundwater is recharged by lateral underground inflow [17, 18] in the area where the hardpan is deep enough at Ljubljansko barje in south and Kamniško-Mengeško polje in the north [18]. However, the underground inflow is still not very well known therefore a study about it should be made in the future. Small water recharge from surrounding hills is present as well. The Sava river is one of the most important sources of groundwater in Ljubljansko polje aquifer system, although it does not recharge the aquifer along its entire length. The Sava river water inflows into the aquifer system between Tacen and Šentjakob [19], while the groundwater recharges the Sava downstream from Šentjakob. It is important to highlight that there are some locations where the Sava's bed lies on the hardpan, therefore no river-ground-water interactions are present. An important loss of groundwater is also water supply. There are four pumping stations in Ljubljansko polje: Kleče, Jarški prod, Hrastje and Šentvid. The largest is in Kleče, where 55 % of drinking water was pumped in 2003 [20]. Figure 1: Map of Ljubljansko polje. Information about geological composition of Ljubljansko polje was taken from previous studies and approximately 115 drilling reports from the Javno podjetje Vodovod-Kanalizaci-ja, d. o. o., (VO-KA) and Pivovarna Union, d. d. Different lithological terms in drilling reports were used in the last 70 years therefore it was first necessary to unify them. Golden Software Strater was used for this purpose. According to all lithological information, the aquifer was divided into five modelled layers presented in Table 1. The aquifer is composed of Holocene and Pleistocene fluvial sediments, while its basement is composed of impermeable rocks (a hardpan). The geometry of the hardpan is diverse, its outcrops are in Šentjakob, Črnuče and Tacen. On the other hand, it is located quite deep, even more than 100 m, in the central part of the aquifer. Three topographic data types, obtained from different institutions/companies, were used for generation the model surface: (1) Digital elevation model (DEM) from The Surveying and Mapping Authority of the Republic of Slovenia; (2) LiDAR data for Sava floodplain from Holding Slovenske elektrarne, d. o. o., (HSE, d. o. o.); and (3) 126 Sava's cross-sections from the City Municipality of Ljubljana (MOL). The precise surface generation of the aquifer is a demanding task and thus presented in the second part of the article. Table 1: Lithological composition of modelled layers (ML) Precise surface generation for modelling The most appropriate GIS data for FEFLOW were prepared in the SHP or DAT files. The model geometry: polygon of the border, lines of the left and right banks of the Sava river, and points of wells and piezometers was constructed using SHP files. The outcrops of the hardpan, the Ljubljanica and Kamniška Bistrica rivers were the main criteria when the border of the study area was defined. The lines were extrapolated from TIN file with the following procedure. Designing a grid is one of the critical steps in groundwater modelling. Although fine grids provide more accurate solutions, the grid should be generated wisely since the duration of calculation depends on number of finite elements. Therefore, it is reasonably to use fine grids where accurate solutions are expected and coarse girds where details are not important [12]. The aquifer domain was discretised by Triangle Mesh Generator, into 96 129 mesh elements per slice or 480 645 mesh element in total. Triangle is an extremely fast meshing tool for complex meshes. It has been developed by Jonathan Richard Shewchuk [21]. The mesh in floodplain domain was refined after the discretization. The reason is higher aquifer vulnerability to pollution at that area. The mesh structure for the Sava river bed has been refined until the mesh was small enough and consequently appropriate for interpolation of the river cross-sections data. The mesh is succinct around pumping wells and piezometers as well, since pumping wells have a great influence on the aquifer and the known elevation of the hydraulic head is important for the model calibration. Figure 2 shows the full map extent of the Ljubljansko No. ML Lithology Epoch 1 Gravel, sand, gravel with sand and silt Holocene 2 Conglomerate, clay, conglomerate with lens and clay 3 Gravel with clay, sand with clay, gravel with narrow lines of conglomerate, gravel with _sand and silt_ Pleistocene 4 Conglomerate is predominate 5 Gravel with sand and silt Figure 2: Two-dimensional view of the Ljubljansko polje model domain with a finite element mesh. polje with aquifer discretization using a finite element mesh. The model domain is greater than 70.85 km2 and it is bounded approximately by the latitudes 46.12° N and 46.08° N and the longitudes 14.43° E and 14.64° E. DEM, Light Detection and Ranging (LiDAR) and the river cross sections were needed for interpolation of a surface, which were obtained as bunch of XYZ, LAS and KOO files, respectively. A XYZ file stores x, y, and z coordinates as floating-point values, where each row represents a distinct point record. A LAS file is an industry-standard binary format for storing airborne LiDAR data [22]. A KOO file is used for storing coordinates in national coordinate system, this is Gauss-Kruger coordinate system in Slovenia. These ASCII files were transformed into SHP files. The transformation of the XYZ and the KOO files is easy, while transformation of LAS files is more demanding. The LAS files were transformed indirectly into the SHP file through Terrain and Raster files. The ArcCata-log is needed for creating the Terrain file and 3D Analysis Tools in ArcMap for transformation Terrain file into the raster file with its anxious resolution. Once the data were imported into the FEFLOW, the surface interpolation was provided using the following steps: (1) interpolation of the full model surface by DEM data (25 m x 25 m); (2) interpolation of the floodplain by LiDAR data (10 m x 10 m); and (3) interpolation of the river bed. AKIMA linear interpolation was used in the first and second steps, while Neighbourhood Relationship interpolation method was used in the third step. Some important properties in Parameter Association should be defined before using Neighbourhood Relationship in- terpolation method: (1) under Default link selection the line among which the interpolation will be done should be chosen, (2) the Snap distance should be at least similar to the largest distance between cross-sections. The distances between the Sava cross-sections range from approximately 20 m to 690 m along the flow path, thus the Snap distance 690 m was used in our case. To find the border between wet and dry region of the river bed is demanding and time-consuming process. For this purpose the 3D Analysis Tool was used for conversion of the Terrain file into TIN file (Triangle Irregular Network). Figure 3 shows the result of the river bed topography interpolation in FEFLOW. Further, nodes for single interpolation should be chosen carefully. To make it easier the SHP files (polygons of the floodplain and the wetted region of the river bed) were made, which enable fast selection of mesh items by map polygon. The Data Management Tool in ArcMap was used, which further enables a fast conversion of lines into a polygon. The counter map of the hardpan defined by hydrogeologists, was reconstructed using: (1) coordinates of later drilled wells that reached the hardpan, and (2) extrapolated outcrops of Figure 3: The Sava river bed terrain a) and in the model b). the hardpan around Ljubljansko polje from the digitalized geological map. Few interpretations of new datasets were made and finally the most reasonable geometry of the hardpan was selected. Conclusion The conceptual model of Ljubljansko polje aquifer system was constructed, which will be progressed into the regional groundwater flow model. The main advantage of conceptual model is the construction of very high resolution of model domain geometry, especially the Sava river topography, which was constructed with river cross-sections data. The hardpan is the basement of the five model layers. The existing counter hardpan map was updated according to later drilling reports and digitalized geological map. However, during a conceptualisation it is necessarily to accept the trade-off among realism, generality and precision [23]. The simplification of a natural system is another great problem for beginners, who do not understand the philosophy of modelling yet - less is more [2]. Extremely high resolution of our model geometry causes instability of the model as well. Therefore, the model geometry had to be reconstructed. When the model geometry was constructed the initial and boundary conditions were defined. In the next step the calibration of the steady state model of groundwater flow will be performed. Acknowledgment The model is under preparation as a part of the ongoing EU 7th Research Project - GLOBAQUA (Managing the effects of multiple stressors on aquatic ecosystem under water scarcity). The project is financially supported by the IAEA Project under Contact No. RER8016 TC entitled 'Using Environmental Isotopes for Evaluation of Streamwater/Groundwater Interactions in Selected Aquifer in the Danube Basin' and Environmental Social Found (KROP 2012). The authors would like to thank all those who provided the data or offered us any other help: Javno podjetje Vodovod-Kanalizacija, Ljubljana, The City Municipality of Ljubljana, Holding Slovenske elektrarne, d. o. o., Pivovarna Union, d. d., Slovenian Environmental Agency, The Surveying and Mapping Authority of the Republic of Slovenia, DHD, d. o. o., and Institute for Water of the Republic of Slovenia. Special thanks go to hydrogeological specialist of Ljubljansko polje aquifer system Mrs Branka Bračič Železnik, who helped us with her professional advices and experience. References [1] L4018/GWM I, Groundwater modelling. 2000. [2] Anderson, M. P., Woessner, W. W. (1992): Applied Groundwater Modelling: simulation of flow and ad-vective transport. San Diego: Elsevier. [3] Kmecl, V., Simončič, A., Sušin, J., Žnidaršič-Pongrac, V. (2005): Rodovitnost tal. Podtalnica Ljubljanskega polja; pp. 164-177. [4] Bračič Železnik, B., Kladnik, D., Rejec Brancelj, I., Smrekar, A. (2005): Mestna raba tal. Podtalnica Ljubljanskega polja; pp. 188-201. [5] Janža, M., Meglič, P., Šram, D. (2015): Numerical hydrological modelling, Final Report [online, cited 2015]. Available on:. [6] Vižintin, G., Souvent P., Veselič, M., Cencur Curk, B. (2009): Determination of urban groundwater pollution in alluvial aquifer using linked process models considering urban water cycle. Journal of Hydrology; 377 (3-4), pp. 261-273. [7] Mikulič, Z., Andjelov, M. (2008): Groundwater modelling. International Symposium on Groundwater Flow and Transport Modelling, Ljubljana. [8] Radinja, D. (1951): Sava na Ljubljanskem polju. Geografski vestnik; 23, pp. M. [9] Žlebnik, L. (1971): Pleistocen Kranjskega, Sorškega in Ljubljanskega polja. Geologija; 17, pp. 477-491. [10] Premru, U. (1983): Osnovna geološka karta SFRJ. Tolmač lista Ljubljana; L 33-66, pp. 111. [11] Konikow, L. F. (1999): Use of numerical models to simulate groundwater flow and transport. In: Yurtsever, Y. (Editor), Modelling. Environmental isotopes in the hydrological cycle: Principles and applications, IAEA. Vienna, pp. 75-115. [12] Faust, C. R., Mercer, J. W. (1980): Ground-Water Modeling: Numerical Models. Ground Water; 18 (4), pp. 395-409. [13] Huyakorn, P. S., Wadsworth, T. D. (1985): FLAMENCO: A three-dimensional finite element code for analyzing water flow and solute transport in saturated-unsatu-rated porous media. GeoTrans, Inc, Herdon. [14] MIKE Provided by DHI [online, cited 2015]. Available on:. [15] ESRI[online, cited 2015]. Available on:. [16] Kete, P., Berk, S. (2012): Stari in novi državni koordinatni system v Republiki Sloveniji ter koordinatni system zveze Nato. Geoprostorska podpora obrambnemu sistemu Republike Slovenije; pp. 259-279. [17] Auersperger, P., Čenčur Curk., B., Jamnik, B., Janža, M., Kus, J., Prestor, J., Urbanc, J. (2005): Dinamika podzemne vode. Podtalnica Ljubljanskega polja; pp. 39-61. [18] Cerar, S., Urbanc, J. (2013): Carbonate Chemistry and isotope characteristics of groundwater of Ljubljans- ko polje and Ljubljansko barje aquifers in Slovenia. The Scientific World Journal; 2013, pp. 1-11. [19] Andjelov, M., Bat, M., Frantar, P., Mikulič, Z., Savić, V., Uhan, J. (2005): Pregled elementov vodne bilance. Podtalnica Ljubljanskega polja, pp. 27-38. [20] Bračič Železnik, B., Jamnik, B. (2005): Javna oskrba s pitno vodo. Podtalnica Ljubljanskega polja; pp. 101-120. [21] FEFLOW Help [online, cited 2015]. Available on:. [22] ArcGIS Help 10.1[online, cited 2015]. Available on:. [23] Levins, R. (1966): The strategy of model-building in population biology. American Scintist; 54 (4), pp. 421-431. Original scientific paper Received: August 4, 2015 Accepted: September 10, 2015 Analyisis of shallow tunnels construction in swelling grounds Analiza gradnje plitvih predorov v nabrekalnih hribinah Jakob Likar1, *, Andrej Likar2, Jože Žarn1, Tina Marolt Čebašek1 University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, 1000 Ljubljana, Slovenia 2Geoportal, d. o. o., Tehnološki park 21, 1000 Ljubljana, Slovenia Corresponding author. E-mail: jakob.likar@ntf.uni-lj.si Abstract Swelling pressures of the rock as a result of chemical and physical processes which are present during construction and operation of tunnels and have the influence on loads and deformations of primary and inner concrete lining. Deep geomechanical analysis of swelling indicates that in practice very often conservative way of calculating load capacity of primary as well as inner lining were used with a goal to keep long-term stability of the tunnel. Particular emphasis was placed on the physical and chemical assessment of the time dependent development of deformation. In the present paper the practical case of tunnel construction in specific swelling clay ground »Sivica« is analyzed. Based on 2D and 3D geostatic analyses, a rigid primary lining was chosen as a final design, because the depth of the tunnel is only about 30 m below the surface. The geotechnical parameters of hoist ground »Sivica« are a result of laboratory and »in situ« tests, which were conducted according to technical standards. During a construction and after it the geotechnical measurements were conducted. The measurement results confirm the correct technical decision in the design stage. Key words: Road tunnel, support elements, Finite Element Method, primary shotcrete lining, geotechnical measurements Izvleček Nabrekalni tlaki v hribinah so rezultat kemijskih in fizikalnih procesov, ki med gradnjo in obratovanjem predorov vplivajo na obtežbe in deformacije, ki se razvijajo tako v primarni kot tudi notranji betonski oblogi. Poglobljene geomehanske analize nabrekalnih pojavov v hribinah so pogosto osnova za konzervativne načine izračuna potrebne nosilnosti primarne in tudi notranje obloge predora z namenom, da se zagotovi dolgoročna stabilnost podzemnega objekta. Posebna pozornost analiz je namenjena fizikalnim in kemijskim procesom v hribinah z nabrekalnim potencialom v odvisnosti od časovno odvisnih deformacij. V tem prispevku je podan praktičen primer gradnje cestnega predora v glinasti hribini »Sivica«, ki ima specifične nabrekalne lastnosti. Končna tehnična rešitev gradnje na osnovi rezultatov geostatičnih analiz 2D in 3D je temeljila na uporabi toge primarne obloge, ker je globina predora le okrog 30 m pod površino terena. Geotehnični parametri »Sivice« so bili določeni z upoštevanjem laboratorijskih in terenskih raziskav, ki so bile izvedene skladno z veljavnimi standardi. Med gradnjo in po njej so bile izvajane ge-otehnične meritve, katerih rezultati so omogočili primerjavo z izračunanimi parametri in posledično potrditev ustreznosti projektnih rešitev. Ključne besede: cestni predor, metoda končnih elementov, primarna obloga iz brizganega betona, geoteh-nične meritve 176 Introduction Understanding the basic theory of chemical and physical processes in swelling ground is fundamental condition for successful technical solution of tunnel construction in such circumstances. When tunneling takes place in swelling ground such as anhydrite or swelling clay minerals, i.e. montmorillonite, whole process of construction, including underground water presence and designed technology, needs to be analyzed. This is very important, because in the past in more cases of tunneling in such grounds, after deep analysis were carried out, clear shown the influence of unusable technology which caused and activated swelling potential of present ground layers (Figure 1). It is known that chemical reaction of anhydrite (CaSO4) in the gypsum (CaS04 • 2H20) results in the increase of volume up to 61 %. The similar can apply in the shale formations with swelling potential where physic-chemical reaction depends on stress relief and reduction of the chloride concentration by water adsorption (osmotic swelling). The chloride ion diffusion is assumed to be the mechanism for the reduction of the chloride concentration. Research activities of swelling processes in ground Numerous calculation methods have been presented in the past to simulate the swelling behavior and the resulting structural response [1-9]. Very important laboratory tests on swelling rocks were done by Barla [10], where swelling gouge from weakness zone in tunnel were investigated. High sophisticated constitutive laws have been developed to account for the phenomenon of swelling in terms of continuum mechanical models, i.e.[12-15]. Several PhD theses were done on the topic of swelling processes in rocks [10, 16, 17], in which authors were explained fundamentals of physical and chemical base of the such ground behavior. More attention is paid on experimental investigation which was done by[18]. He had shown the compression and swelling behavior of the Callovo-Oxfordian argillite. Two series of oedometric tests were carried out, first one showed that the argillite exhibits a swelling behavior even when fully saturated under stresses higher than the in-si-tu stress, and the second series of tests showed that the swelling capacity appeared to increase with compression. In both cases, swelling was related either to pre-existing cracks due to sample coring, storage, drying, wetting and trimming or to cracks induced during compression. In this regard, compression was suspected to occur by local pore collapse that created micro-cracks that afterwards swelled when hydrated. Indeed, sample compressed to a higher pressure exhibited higher swelling potential. A high quality investigation of swelling phenomena was carried out[19] which focused on repair works done in old railway tunnel in Switzerland. Long-term laboratory tests showed that the swelling behaviour occurred in stages and bands of precipitated gypsum were found in samples analysed by mineralogical test after test completion [20]. The swelling processes require water and this could be facilitated by spalling type fractures, brittle failure behaviour with associated extensional fracture development as a potentially controlling mechanism in creating a water conductive zone beneath the tunnel invert. Such brittle fractures were observed during tunnel construction in anhydrite by[21, 22]. Therefore, gypsum crystal growth is most likely to occur where water has access (a) flexible flat-slab heave (b> rigid invert-arch heave and failure m rigid circular section heave and displacement as riciid bod v Figure 1: Typical events associated with swelling in tunnels according to 177 and the state of stress is favourable for stress fracturing. On the low confinement side of the spalling limit, water has access through fractured ground and the rock mass is essentially free swelling until the support provides sufficient pressure to prevent further swelling. One of the important investigation of swelling phenomena was relating to the goal of the presented investigations and that is to describe the phenomenon of self-sealing quantitatively (Figure 2, 3) and to establish a model, by means of which it is possible to take the self-sealing phenomenon into account when designing tunnels in swelling rock[23, 24]. It is expected, that due to the new models a more effective and economic design of tunnels in swelling rock will be possible. Swelling pressures, which had been identified in some old railway tunnels that were built in the 19th and in the early years of the 20 th century, manifested in many cases, particularly in the floor inverts. In some cases it was necessary to carry out rehabilitation even twice, because the invert had shallow arch which hadn't enough сок praktisch undurclilä&Ejg (Folge der SelbslabdichlunB) ' pratile all у impermeable due to sc If-scaling АиэШ i;. ngHH inching front Arhydritspiogcl anhydrite level quellfähig ■welling rock iDolaiMljDolail Jl [Detail 3] ш ITunrwlj Aunockerung&zofie loosened »ne I ! ; Figure 2: Mechanisms of self-sealing in SBR[231. Detail 2 static resistance of the support ring (Wagenburgtunnel, built in 1957][26]. From several analyzed cases it can be summarized that the process of swelling is usually intensely present in the floor and in the sides of the underground facility, which represents lower static capacity of the structure. Special case of tunnel construction in swelling rocks was Engelbergtunnel tunnel, which was built in 1990 [26]. The primary lining has been damaged at the beginning of construction at the connection point between the tunnel side the tunnel invert. At the beginning the original basic design was based on dry rock conditions during construction. Furthermore, in the upper design stage it was planned inner lining of reinforced concrete in the goal to excluding the effect of swelling pressure of the surrounding rock. During the construction phase, the design concept was significantly revised since instead of 30 cm thick shotcrete lining in the invert, 1.5 m thick concrete lining was installed, additionally anchored in the foundation ground. This way sufficient static resistance to swelling pressures was provided. Above anchored and reinforced invert high deformable layer called »Knautschzone« was constructed to prevent possible damages on the inner lining. And finally, the inner lining in invert was installed with a thickness of 3 m, as shown in Figure 4. In the design procedure is important question when in case of construction of the underground facility the increment of the volume change will be prevented enough with the installation of rigid support system in the goal to reduced deformation in acceptable limit. That requirement in the conclusion still need adequate primary lining with sufficient load bearing capacity to ensure stability during the construction. It should be noted that the time evolution of swelling pressures depends on the amount of water in contact with swelling ground and stiffness properties of the primary lining. This takes into account the principle of long-term stability of the facility with the primary lining, which consists of a standard shotcrete lining, steel arches, steel wire mesh and rock bolts or anchors. A typical example of the combination of swelling and squeezing rocks can be found in Karavanke road tunnel connecting Slovenia and Austria, which was built in the second half of the 1980s and put in operation in 1991. In fact is that deformations, which in some sections had started to develop immediately after completion of construction or even already in the time of construction did not stabilize. The continuous time developed deformations called for the implementation of the rehabilitation of certain sections. Measurements which were carried out in the last years showed that the deformation process after refurbishment not stopped in some sections. Due to difficulties in identifying key parameters for such swelling laws the engineering approach predicting the swelling pressure used back-calculation of data monitored during construction of the tunnel in similar ground conditions. The last investigations in the Karavanke tunnel have shown that installation of a deformable layer in the invert between surroundings rocks and refurbished primary lining can be right technical solution for time stable tunnel structure. Figure 4: Construction the Engelbergtunnel1231. Basic principles of support system design in swelling ground The primary mode of support system planning is based on the principle of ensuring a balance between swelling capacity of ground and reacting support pressure. It is exposed to the volume increase that occurs after the excavation step. The relationship swelling ground - support system has important influence on the location of the equilibrium system, as shown in the Figure 5. It should be noted that the release of ground strain is a result of mobilization bearing capacity of the ground and at the same time swelling forces are generated when water or air moisture find the contact with ground surface at the excavation round in the tunnel. Quick and effective prevention of water access indirectly reduces formation of higher swelling pressures relating to formation efficient activation of the self-protection ground layer around tunnel wall. Exactly that self-protective effect has a unique role on reaching equilibrium between the supports system and surrounding ground. Swelling phenomena aplication in the tunnel Ljubno design The presented case of the shallow tunnel Ljubno with maximum overburden of about 30 m was built in the ground with swelling potential in the northern part of motorway section A2 Karavanke (Austria] - Obrežje (Croatia), and has shown specific circumstances relating to geotechnical conditions assessment. The new Tunnel Ljubno was built as the twine road tunnel including reconstruction of the old tunnel tube which is now a part of new motorway (Figure 6]. The old tunnel tube was constructed in the 60s of the past century without invert (Figure 6]. In more than 40 years that the tunnel was in operation damages such as lifting of the pavement similar as shown in Figure 1-a) occurred. Reconstruction of the old tunnel tube included extension of the current clearance profile according to the standard that requires two lanes with a width of 3.75 m, one intervention lane with a width of 3.20 m and two intervention corridors with a width of 0.8 m which is the same as in the new tunnel which was built 40 m away. The amount of excavated material in the profile is approximately 86 m2 per running meter of the tunnel. Results of geological and geotechnical investigation In order to design construction and reconstruction of tunnel tubes extensive field and laboratory investigations and explorations Elk, = Elastic strain Ei^mix = Maximum swelling strain from edometer test Figure 5: Basic principle of tunnel support design in swelling ground. Figure 6: Location of the new and old tunnel tube with maximum overburden of about 30 m and clearance profiles of the old tunnel before reconstruction and after it. were carried out to determine geological and geotechnical characteristic of ground materials present in the tunnel area. All investigations and geostatic analysis were carried out before the design of new tunnel tube which was constructed first before the reconstruction of old tunnel tube begun. Special attention was paid to the investigation of hard clay known as »Sivica« in which majority of the excavation works were done. Design of excavation and primary support lining was done in an appropriate way due to extensive amount of information acquired by geological mapping, boreholes drilling, Standard Penetration Tests and Pres-suremeter Tests. The prognosis of geological structure is shown on the longitudinal profile in Figure 7. Distance between tunnel tubes is shown in the Figure 8. The laboratory tests included measurements of moisture content, UCS, Triaxial Shear Tests and particularly attention was paid to the measurements of swelling potential and deformability of »Sivica«. It was found that in a dry environment »Sivica« has solid strength properties, while contact with water causes the relatively high presence of swelling potential. A large number Figure 7: Longitudinal geological profile of the new tunnel tube. Table 1: Basic geotechnical parameters of the existing ground layers Type of ground Moisture w/% Unit weight Y/ (kN/m3) Youg Modulus E/MPa Poisson ratio V Tensile strenght fft/MPa Unconfined compresive strenght ff/MPa Angle of internal friction ф/° Cohesion c/MPa Silty clay 25.0 20.0 5.0 0.4 / 0.001 25.0 0.0 Conglomerat / 25.0 4 000.0 0.2 / / 40.0 0.5 »Sivica« 7.0 24.0 200.0 0.3 0.5 5.0 31.0 0.136 Weathered »Sivica« / 20.0 4.0 0.4 / / 23.0 0.0 Table 2: Laboratory determined sweling pressure at prevented strains and swelling strains in the unloading stress conditions Depth below the ground (m) (»Sivica«) Primary vertical ground pressure ffv/MPa Swelling pressure psw/MPa at total prevented strains Swelling strain £sw/% at water presece at total first unloading/second unloading conditions 25.0 0.600 0.250 2.0/3.5 20.0 0.480 0.350 2.0/4.0 16.0 0.385 1.45 1.8 /2.0 33.0 0.800 > 1.5 1.3/4.0 of laboratory tests to describe rock properties including swelling had been performed. The results were represented in Table 1 and Table 2. One of the most important investigations was XRD Analysis which was carried out with the goal to determine the mineralogical content of the »Sivica« sediment samples. The diffraction patterns were identified with the data from X'Pert HighScore Plus software ICDD database. The compact gray clay samples were analysed with handheld XRF analyser NI TON GOLDD+ model XL3t He (50 kV) for major and minor element concentrations. The XRF result represents average of four measurements. Analy- Figure 8: Vertical cross section through existing (right) and new tunnel tube (left) with low overburden. ses were run with helium purge in the XRF in order to determine the degree of improvement in the signal detection attributable to helium's elimination of scattering by atmospheric gases. The analyser uses a 50 keV miniaturized X-ray tube and can quantify elements from magnesium through uranium. Data for all experiments consisted of counts (of X-ray fluorescence) detected per second. Total acquisition times were kept constant at 180 s. Bal variable is balance and incorporates all light elements from H to Na that cannot be detected with this XRF analyser. Based on given results as shown on Figure 10 the conclusion has shown that fresh clay sample does not contain any swelling minerals. The clinochlore (chlorite) in the clay sample does not change volume upon solvation with ethylene glycol, but only with the addition of water. When the chlorite mineral in the clay is altered by surface weathering, the alteration in the slate appears to be relatively rapid and complete. Direct surface exposure of the clay leads to the apparent irreversible dehydration of the surface layer of the clay. Weathering procedure is the manner in which chlorite ordinary alters when subjected to an atmospheric environment. It seems that alteration of chlorite leads to formation of mixed-layer chlorite-vermic-ulite and possibly to montmorillonite (Mg-sa-ponite) which are well known swelling clay minerals. From the results revealed the presence of swelling potential (Figure 9) and investigation based on XRF analyser (Figure 10), it cannot clear demonstrate the unique possibilities of activation swelling process during construction or reconstruction the tunnel tubes. Taking into account all results of swelling potential analysis, back geotechnical analysis of stability the old tunnel tube (Figure 5) and considerations in the mentioned scientific founding published in adequate journals in the deeper geotech-nical design analysis used swelling pressure p = 1 200 kPa. I sw Figure 9: Laboratory test results of swelling potential of the dark grey hart clay »Sivica« on the sample from the depth 33.0-33.3 m below the ground surface which is close to tunnel tubes locations. Designed solution for tunnel construction and reconstruction Due to the expected behaviour of »Sivica« the design provided technological measures to reduce the danger of water influence on the strength of the intact geological material. Immediately after excavation free surface was protected with shotcrete. Drilling and anchoring techniques without water usage were implemented. The purpose of these measures was to avoid contact between ground and any type of water and thus keep »Sivica« in its natural conditions. The basis for determining the swelling ground - support system relationship is a relation between the reactive support pressure and the tunnel wall deformations, as shown in the Figure 11 which is prepared on the basis of assessment usable swelling pressure including in accounting the stiffness of primary shotcrete lining. For assessment of relevant value of design swelling pressure, the elastic pre-defor-mations e . = 0.4 % and stiffness of shotcrete ui primary lining kc = 540 MPa with adequate Esw = 0.3 % radial strains were used in the equations based on close form solution method. The geostatic primary vertical pressure in the rock and the additional swelling pressure which was obtained from laboratory tests (Table 2] were included in the geostatic calculations. The reduction of reaction support pressure was achieved by introducing the flexibility of the primary support system. Reserves in the capacity of proposed support system were established with a safety factor against the collapse. That was applied during the calculation of internal forces and bending moments from the results of 3D geostatic analyses which are described in the next subsection. Determination of the size of the damaged zone around the tunnel lining in the old tunnel tube was determined based on the examination of drilling cores, which have been acquired in the research stage of design. Figure 10: Result of XRFanalysis. Figure 11: Designed support measures for essential length of tunnel. This ranged from 0.5 m to the on the tunnel roof and around 1.0 m on the tunnel sides and in the floor without invert. During the reconstruction of the old tunnel tubes (Figure 13) the damaged layer around the old tunnel was removed, which is favourable for the establishment of long-term geostatic stability the tunnel system (Figure 12). Based on the analysis of different theoretical approaches and practical cases of tunnel construction in swelling grounds including the geometrical data and thickness of ground layers cover, the rigid support system was applied. To follow this goal, the standard supporting elements have been considered in the design such as steel arches K24 and sprayed cement concrete thickness between 30 cm and 35 cm with two layers of wire meshes and rock bolts if required (Figure 11). The whole length of the tunnel tubes was scheduled with invert built from shotcrete with the same thickness. Rock classification was made according to Austrian standards OENORM B 2203. Geostatic analysis of tunnels support measures To verify the support measures designed as primary lining, extensive 2D and 3D numeric analyses, using Phase2D and MIDAS GTS computers codes, were done. The comparison between load cases without and with considering additional pressures caused by swelling (340 kPa) were carried out for two different design solutions. The swelling pressure was simulated with j DESIGN RIGID SUPPORT 5VSTEM SWELLING PRESSURE iWinOSTATIC GROUND PRESSURE ---Г-----TOtAL PHES5LIRE GROUND PRESSURE \ DESIGN POUT • JONU№RJtAL «UALVSIS f- 41 { RADIAL STflAJN i Ел FtAQiu STWIN-GEOSTATIC PRESSURE e*. _ ÌRAHAL ST RAIN - SWELLING PRESSURE proportionally higher unit weight of ground. In the Table 3 and Table 4 input ground geotechnical data for both numeric analyses are shown. The excavation of the tunnel was divided into a top heading, bench and invert, while on the longitudinal direction the excavation was simulated in progressive steps of 2 m in length. The support elements in the calculations were planned with reinforced shotcrete lining with two steel meshes. Figures 14 and 15 shows the results of the calculation displacements without and with swelling pressure considered. In the first case the displacement could reach the value of 3.0 cm in the invert and, while in the second case, displacements were below 6.5 cm. The values of displacement for both calculations are shown in the Table 5. From the same figures the area of influence of tunnel excavation is in the worst case stretched up to 15 m left and right of the planed axis of the new tunnel, which means that the new tunnel tube excavation on the existing tunnel tube practically hasn't effect on stress-strain changes. The same can be concluded from the Figures 16 and 17, where the calculated Strength Factor (SF) is shown. If the values and distribution of main stresses Sigma 1 and Sigma 3, FS and total displacements around tunnel tubes are compared with each other, it is evident that the main concentration are present in the invert area. This is mostly related to shallow depth of the tunnel locations and stiff static resistivity of primary linings incorporated in the low bearing capacity of surrounding ground. 3D FEM analysis were carried out in the similar way as 2D calculations. The first numerical simulation was done when the excavation procedure of the new tunnel tube was analyzed. Calculated total diplacement which are shown in Figure 18 has the maximum value approx. 8.5 cm in the invert and the minimum value approx. 3.0 cm on the crown. In the next short presentations of calculations results we can find that higher stresses and strains in the primary lining existed in the roof and invert parts of tunnels tubes (Figure 19 and 20). That are comparable with results of 2D analysis which were shown in Figure 14 to 17. Figure 12: Reactive support pressure versus radial strain in the swelling ground. Table 3: Input geotechnical ground data for the analysis Type of ground Unit weight y/(kN/m3) Young Modulus E/MPa Poisson ratio v Cohesion c/kPa Angle of internal friction ф/° Silt 20 5 0.4 1.0 25 Conglomerat 25 4 000 0.2 500.0 40 Sivica 24 200 0.3 136.0 31 Table 4: Mechanical parameters of support elements Support element Unit weight y/(kN/m3) Young Modulus E/MPa Poisson ratio v Thick of primary lining (m) Wire mesh Q189 (pcs.) Shotcrete (fresh) 25 3 000 0.30 0.35 Shotcrete (final) 25 15 000 0.25 0.35 Table 5: Calculated displacements in the invert and side walls Calculated maximum displacements (cm) Object without swelling with swelling invert side wall invert side wall New tunnel tube 3.0 1.1 6.2 2.3 Reconstructed tunnel tube 1.1 0.7 1.4 1.0 The results of 3D simulations of the excavation and primary support installation for new and reshaped tunnel tube with respect to the swelling pressure of the surrounding rock are calculated depending on the depth and characteris- tics of »Sivica« and the size of the tunnel tubes. For both tunnel tubes calculated total displacements are between 2 cm and 6 cm at the roof and invert (Figure 21). Figure 14: Calculated displacements in the new and reconstructed tunnel tube without taking into account designed swelling pressure. Figure 16: Calculated Strength Factor (SF) in the ground for the new and reconstructed tunnel tube without taking into account designed swelling pressure. m a M a ■ £ л а в Figure 17: Calculated Strength Factor (SF) in the ground for the new and reconstructed tunnel tube with taking into account designed swelling pressure. Figure 18: Total displacements after excavation and support of the new tunnel (left tube direction toward Ljubljana). The maximum axial forces in the primary lining were found in the both sides where the calculated values are around -5 000 kN. While the smallest values of calculation results are shown in the roof and in the invert of tunnel tubes which amount to around -300kN. It is worth noting, as their value is very small and is close to the tension zone, which is which is compensated by a double reinforcement wire mesh, so that provides sufficient safety against Figure 21: Total displacements after excavation and support of the right tube (direction toward Ljubljana). Figure 22: Tangential axial forces in primary lining - left and Figure 23: Bending moments in primary lining - left and right tube after excavation and support of the old one tunnel right tube after excavation and support of the right tube. (right tube - direction toward Ljubljana). the development of tensile cracks. Particular attention was dedicated to the construction of joint primary lining in contact between top heading and bench with invert. The results are shown in Figure22. Analysis of the bending moments in the primary support shows that in the ceiling value regardless of the format of a positive in ground vault but negative. Their value ranges from about +82 kN m/m to about -122 kNm/m, which is not a problem for the provision of required stability (Figure 23). Some distinctive features of the construction A relatively short length of the tunnel was not suited for performing excavation with several phases going on simultaneously. Therefore, the excavation of the concrete invert was made first, followed by making a bench and top head- ing which were constructed together. Since the northern portal was not accessible, the whole excavation was made from the southern portal running towards the northern portal, where the breakthrough was made directly to the surface, meaning that no previous protective measures were necessary on the northern portal. Figure24 shows the breakthrough of the top heading in the inaccessible area. The last few metres of the top heading were built in the side gallery, with the cross section profile of approx. one third of the cross section of the top heading. This method of excavation reduced the risk of overbreak during the breakthrough. The breakthrough, as well as the excavation of northern portal and excavation of the remaining top heading of the tunnel, were made successively. 1 irr LEFT TUBE RIGHT TUBE _ÜS BI 1___^ ——"l —1— 1 4— f >7 -- Л ISO г--1- -1- - ■--л - «ы Figure 24: Excavation face and breakthrough at the Nord portal of the new tunnel tube and reconstruction of the old tunnel. TANGENTIAL STRESSES IN THE PRIMARY LINING Figure 25: Measurement results of additional circular and radial stresses in the contact between ground and primary lining in the new tunnel tube. Gelogical observations and geotechnical measurement during construction and in operation The results of monitoring measurements in pressure cells (and extensometers), which were installed during the construction of the new tunnel tube in the same geological geotechnical conditions did not show additional increases in circular (tangential) and radial stress (Figure 25 and 26) as a result of influence of the reconstruction of old tunnel. In future the swelling potential will not produce additional stresses on the inner lining, because the primary lining has a sufficient loading capacity. The process which explains swelling pressure increase in examined ground shows that the closure of cracks depends of ground water isolation. This is consistent with the results of extensive research of various swelling rock types [25, 26], which have rheological properties similar to hard clay (Sivica). It has been proven that naturally developed swelling pressures are much lower or minimum than those which are obtained from laboratory investigations. The determination of meaningful swelling pressure to be applied to the tunnel lining based on laboratory tests is largely depending on the scale effect, the stiffness ratio of the tunnel lining and surrounding ground and the in-situ stress and water conditions. Hence, swelling load conditions are difficult to predict in the reality. The displacements measured during the excavation were smaller than expected, i.e. less than 3 cm. This is probably due to more favourable geological and geotechnical conditions and high level of technological discipline of contractor. Measurements of displacements over time proved that the process slowed down and practically stopped one week after the excavation, with- TANGENTIAL STRESSES IN THE PRIMARY LINING 0.90 1 .jan.10 15.jan.10 29.jan.10 12.feb.10 26.feb.10 12.mar.10 26.mar.10 Э.арг.Ю 23.apr.10 7.rnaj.10 21.maj.10 4.jun.10 Date of measurments —D— SMS X SMh —•— SM / —•—SM 1 —*— SM V Ж SM4 -1-SMH Figure 26: Measurement results of additional circular and radial stresses in the contact between ground and primary lining in the reconstructed tunnel tube. out any significant deviations. The excavation of the bench was followed by the excavation of the concrete invert and building of the foundations and concrete invert, at a suitable distance of about 30 m to 40 m. During the excavation of the new tunnel tube, displacements of the lining in the adjacent existing tunnel tube have been monitored. Only minimal displacements have been noticed, mainly caused by vibrations and due to precise measurements and inaccessibility of the measuring points. The results of measurements have shown that the construction of the new tunnel tube has no impact on the existing tunnel. Conclusions In recent decades many studies were conducted relating to investigation of the construction of tunnels in the swelling rocks. The main goal of these investigations was determination the effects of chemical and physical processes on the swelling pressure development with time. The essential distinction in the design of tunnels in the swelling grounds is depth i.e. primary stress state in grounds layer and other geological and geomechanical properties of geological materials. Different approaches to research, interpretation of their results and suggesting methods of tunnel construction in these types of grounds are a good basis for the construction method decision for each case separately. Substantial progress in understanding the development of swelling pressure is taken into account self- closure effect. This is important for the proper selection of construction technologies which should be at the time of construction imposed to strict control. Successfully design and build a new tunnel tube and reconstruction of an old tunnel tube of the road tunnel Ljubno in the dark gray clay »Sivica« with swelling potential, is an example of good engineering practice in the construction of shallow tunnels in swelling rocks. References [1] Einstein, H. H., Bischoff, N. (1975): Design of Tunnels in Swelling Rocks. 16th Symposium on Rock Mechanics; University of Minnesota, Minneapolis, MN, pp. 185-195 [2] Einstein, H. H. (1996): Tunnelling in difficult ground - Swelling behaviour and identification of swelling rocks. Rock mechanics and rock engineering; 29 (3), pp. 13-124. [3] Gysel, M., (1987): Design of tunnels in swelling rock. Rock Mech. Rock Eng.; 20 (4), pp. 219-242. [4] Kovari, K, Amstad, C, Anagnostou, G (1988). Design/ construction methods - Tunnelling in swelling rocks. In: Cundall et al. (eds) Key Questions in Rock Mechanics: The 29th US Symposium on Rock Mechanics Balkema, Rotterdam, pp. 17-31. [5] Lombardi, G. (1984): Underground openings in swelling rock. Proc. 1st Nat. Conf. on Case Histories in Geotechnical Engineering. Lahore, Pakistan. [6] ISRM (1983): Characterisation of Swelling Rock. Commission on Swelling Rock. Pergamon Press. Oxford, U.K. [7] ISRM (1989): Suggested methods for laboratory testing of argillaceous swelling rocks. Commission on Swelling Rock. Co-ordinator: H. Einstein. Int. J. Rock Mech. Min. Sci. & Goemech. Abstr.; 26 (5), pp. 415-426. [8] ISRM (1994a): Comments and recommendations on design and analysis procedures for structures in argillaceous swelling rock. Commission on Swelling Rock. Co-ordinator: H. Einstein. Int. J. Rock Mech. and Sci. & Geomech. Abstr.; 36, pp. 293-306. [9] ISRM (1994b). Suggested methods for rapid field identification of swelling and slaking rocks. Commission on Swelling Rock. Co-ordinator: H. Einstein. Int. J. Rock Mech. and Min. Sci. & Geomech. Abstr.; 31, pp. 545-548. [10] Barla, M. (1999): Tunnels in Swelling Ground -Simulation of 3D Stress Paths by Triaxial Laboratory Testing. Ph. D. Thesis. Politecnico di Torino. [11] Amstad, C., Kovari, K., (2001): Untertagbau in quellfähigem Fels, Forschungsbericht 52/94, Bundesamt für Strassen (ASTRA) Bern. [12] Grunicke, U., Walter W. and Hofstetter G. (2002): Design of Tunnels in Swelling Rock, Felsbau; 20 (6), pp. 25-34. [13] Anagnostou, G. (2007): Zur Problematik des Tunnelbaus in quellfähigem Gebirge, Mitteilungen der Schweiz. Ges. für Boden- und Felsmechanik, Band 154. [14] Heidkamp, H., Katz, C. (2004): The swelling phenomenon of soils - Proposal of an efficient continuum modelling approach, EUROCK 2004 & 53rd Geome-chanics Colloquium. [15] Wittke-Gattermann, P. and Wittke, M. (2004): Computation of Strains and Pressures for Tunnels in Swelling Rocks. ITA-AITES congress, pp. E14 1-8. [16] Bellwald, P. (1990): A contribution to the design of tunnels in argillaceous rock. Ph.D. Thesis. Massachusetts Institute of technology, Boston, USA. [17] Aristorenas, G. V. (1989): Rheological modelling of swelling rocks. Internal report, Massachusetts Institute of Technology. Boston, USA. Unpublished, included as Chap. 2 in Aristorenas 1992. [18] M. Mohajerani et al. (2011): Oedometric compression and swelling behaviour of the Callovo-Oxfordian argillite. International Journal of Rock Mechanics and Mining Sciences; 48 (4), pp. 606-615. [19] Steiner, W. (1993): Swelling rock in tunnels: Characterization, effect of horizontal stresses and Construction Procedures. Int. J. of Rock Mech.s and Min. Sciences & Geomech. Abstracts; 30 (4), pp. 361-380. [20] Nüesch, R., Steiner, W., Madsen, F. (1995): Long time swelling of anhydritic rock, mineralogical and micro-structural evaluation, Proc. 8th Int. Conference on Rock Mech., Tokyo, Japan, pp. 133-138. [21] Grob, H. (1972): Schwelldruck im Belchentunnel. Int. Symposium für Untertagebau, Luzern, Schweiz, pp. 99-119. [22] Spaun, G. (1974): Über die Ursachen von Sohlhebungen in Tunneln der Gipskeupers. Festschrift Leopold Müller-Salzburg zum 65. Geburtstag, Karlsruhe, pp. 245-260. [23] Wittke, M. (2003): Begrenzung der Quelldriicke durch Selbstabdichtung beim Tunnelbau im anhydritfiihren-den Gebirge. WBI Print 13.2 vols. Gluckauf. 112. [24] Wittke, W. (2007): New high-speed railway lines Stuttgart 21 and Wendlingen-Ulm - Approximately 100 km of tunnels, in Underground Space. - The 4th Dimension of Metropolises, Proceedings of the World Tunnel Congress 2007 and 33rd ITA/AITES Annual General Assembly, Prague, May 2007, edited by J. Bartak, I. Hrdina, G. Romancov, and J. Zlamal, pp. 771-778, Taylor & Francis, London, UK. [25] Wittke, W. (2000): Swelling Stability Analysis for Tunnels - Fundamentals. Verlag Glu'ckauf GmbH, Essen, Germany. [26] Wittke, M. (2002): Design of tunnels in swelling rock, Porc. NUMGE 2002, 5th European Conference on Numerical Methods in Geotechnical Engineering. Professional paper Received: March 9, 2014 Accepted: October 2, 2015 Geological setting, compositional features and economic evaluation of marble deposits around Alaguntan, southwestern Nigeria Geološka lega, značilnosti sestave in gospodarska ocena nahajališč marmorja v okolici Alaguntana v jugozahodni Nigeriji Olugbenga Okunlola1,* and Hafsat Muritala1 University of Ibadan, Department of Geology, Nigeria Corresponding author. E-mail: gbengaokunlola@yahoo.co.uk Abstract Marble, occurring up to 5 000 m long and up to 30 m thick lenses within gneisses and other metasediments in Alaguntan area, southwest Nigeria, have been studied with the aim of investigating their compositional and industrial characteristics . From X-ray Diffraction studies, the marble is composed dominantly of dolomite (95.67 %) with minor amount (up to 1.95 %) of calcite, tremolite, quartz, and actino-lite. Chemical analytical results using Inductive Coupled Plasma Mass Spectrometry (ICPMS) confirm the miner-alogical dolomitic nature with Ca++ /Mg++ (1 : 1.39) and average CaMg(CO3)2 content of 95.69 %. Physical and mechanical tests reveal that the marble samples have effective porosity between 0.51 % and 0.76 %, hardness according to Mohs's scale is 3.0, compressive strength is between 87.53 MPa and 92.72 MPa, confirming their suitability for construction purposes. Further chemical and agronomic tests show the milled marble samples are useful in soil acidity neutralizations and in metallurgy for production of refractory lime and chemicals, manufacture for production of chemicals. Key words: Nigeria, marble, composition, industrial use, deposits Izvleček Marmor, ki ga najdemo v lečah, dolgih do 5 000 m in debelih do 30 m v gnajsih in drugih metasedimentnih kamninah na območju Alaguntana v jugozahodni Nigeriji, smo preučevali za oceno značilnosti njegove sestave in industrijske uporabnosti. Preiskava z rentgensko difrakcijo pokaže, da sestoji marmor pretežno iz dolomita (95,67 %) z majhno količino (do 1,95 %) kalcita, tremolita, kremena in akti-nolita. Rezultati kemične analize z induktivno vezano plazemsko masno spektrometrijo (ICPMS) potrjujejo mineraloško ugotovljeno dolomitno naravo kamnine z razmerjem Ca++/Mg++ 1 : 1,39 in povprečno vsebnostjo CaMg(CO3)2 95,69 %. Fizikalni in mehanični preizkusi kažejo v vzorcih marmorja efektivno poroznost med 0,51 % in 0,76 %, trdoto 3,0 po Mohsovi lestvici in stisljivo trdnost med 87,53 MPa in 92,72 MPa, kar potrjuje njihovo primernost za uporabo v gradbeništvu. Nadaljnje kemične in pedološke preiskave pričajo o uporabnosti mletega marmorja za nevtralizacijo kislosti tal, v metalurgiji za proizvodnjo ognjevzdržnih snovi in za proizvodnjo kemikalij. Ključne besede: Nigerija, marmor, sestava, industrijska uporabnost, nahajališča Introduction Marble deposits globally, have attracted reasonable economic interest and have been classified under six main general areas of applications based on application in industry namely: metallurgical, chemical, environmental, constructional, and agricultural [1, 2]. Metamorphosed carbonate deposits (marbles) in Nigeria generally are found within the eastern margin of the Nigerian Schist belts. (Figure 1) The Schist belts occupy generally N-S trending troughs infolded into the migma-tite-gneiss-complex and are best developed in western half of the country [2, 3]. Recently, we have identified some metamorphosed carbonate deposits (marble) in Alaguntan area in the southwest of Nigeria. The deposits are being studied to unravel the geologic setting, miner-alogical variation and chemical quality with a view to find the potential industrial application of the marble. Marble occurs as lensoidal body similar to other prominent marble deposits in the eastern margins of the Nigerian Schist belt around Igarra, Kwakuti, Ubo, Igbetti, Osara, Jak-ura and Burum[4]. Materials and methods Field sampling and sample preparation About 25 fresh representative rock chips of white and grey marble samples and the selected representative host rocks were collected from Figure 1: Geological map of Nigeria showing the Schist belts (after Turner 1983). RMZ - M&G | 2015 | Vol. 62 | pp. 193-204 different portion of the mapped area around Alaguntan. For sample preparation, 100 g from each of the representative marble sample were pulverised below 100 цт for the mineralogical, chemical and agronomical studies. Thin sections of representative samples of associated host rocks were studied microscopically. Mineralogical analyses were also carried out using X-ray diffraction (XRD) and chemical analyses by Inductive Coupled Plasma Mass Spectrometry (ICPMS) analytical techniques. Both analyses were carried out in Acme Analytical Laboratories Vancouver, Canada. The XRD was done using Siemens D500 diffractometer. Effective porosity and bulk density were determined by immersing an oven dried sample with the mass about 200 g in water for 24 h, till it attains a constant mass. This was re-dried after removal and weight again. The fraction increase in mass relative to the original mass of sample was determined. The ratio of the original sample mass and water volume change was calculated as the Bulk density. Loss on ignition was determined by heating the weighted samples in a furnace and the temperature set at 1 000 °C and fired for an hour. After an hour, the furnace was switched off for 30 min, after which the samples were packed from the furnace into a dessicator, covered to air tight and then allowed to cool in the dessi-cator for an hour, another measurement was taken to get the mass loss. All the physical and geotechnical tests on the marbles were carried out in the Department of Geology, Federal University of Technology, Akure, Nigeria. Agronomical characteristics/parameters determination was done at the Institute of Agricultural Research and Training, Ibadan, by mixing 50 g of acidic soil samples of pH (5.9) collected within the University of Ibadan, Ibadan, premises with 20 g of 90-mesh Alaguntan marble samples and 50 ml of distilled water added for a period of 8 weeks. Major and minor soil nutrient were determined using Atomic Absorption Spectrometry (AAS) and Flame Photometry. Organic matter content, Cation Exchange Capacity, Conductivity, Base saturation were further assessed. The tests were carried out at the soil laboratory, Department of Agronomy, University of Ibadan. Results and Discussion Geological setting The Alaguntan marbles and associated gneisses are part of the Precambrian basement rocks of Nigeria, which is situated in the pre-drift mobile belt that separate West Africa and Congo Cratons [5]. On the basis of structural, lithostratigraphic and geochemical data, and available geochronology data, the Precambrian basement complex of Nigeria have indicated polycyclic nature with multi orogenic events. The rocks of Nigeria have been regionally classified into three major groups namely: Migma-tite Gneiss Complex, Metasedimentary and Me-tavolcanic rocks (Schist belts), and Pan African Granitoids / Older Granites [2] (Figure 1). The schist belts show distinctive petrologi-cal, structural and metallogenic features. The schist belt is dominated by low grade metasediments, remnants of reworked supracrustal cover during the Pan African Orogeny. The schists belt in the southwest include those of the Iseyin, Igara, Egbe-Isanlu, Ife-Ilesha areas [2, 5' 6]. The centrally located ones include the Lokoja-Jakura, and Toto-Gadabuike belts [4, 7 8]). Some of the belts have also been identified in the southeastern parts of the country though not shown in Figure 1[9, 10]. In the area of study, outcropping rocks include: Hornblende biotite gneiss, Granite gneiss, Quartzite, Calc silicate gneiss, Marble and Quartz veins (Figure 2). The marble outcrops are positioned within the granite gneiss (Figure 2). Hornblende biotite Gneiss is the most common rock type mapped, it covers the northern and northeastern parts of the studied area. The extensive outcrops occur as low lying unit, well foliated with preferred orientation of the platy biotite and prismatic hornblende. Thin section studies show the samples are made up of quartz (20 %), biotite 17 %, plagioclase 30 %, hornblende 20 %, and minor amount of muscovite 3 %. The Granite gneisses occupy the southern and southwestern part of the studied area. It is found as low lying outcrops at Aloba not far away to Alaguntan village. It is medium grained in texture with irregular bands rich in biotite and hornblende and are found to alternate with thicker bands richer in felsic minerals. The mineral assemblages includes: quartz 40 %, biotite 20 %, microcline 17 %, plagioclase feldspar 10 %, and muscovite 10 %. Quartzite outcrops occur sub parallel to the calc-silicate rock and marble bodies. They occur as elongated lensoidal bodies up to 30 m thick and about 1.5 km long parallel to the calc-sil-icate rock with a displacement along shear zones between the marble bodies. The contact with the marble is tectonic and is marked by the development of silicified mylonites. Mineral composition is dominantly quartz with accessory muscovite mica i J Quartz Vein Marble Cale Silicate [ 1 Quartzite Granita Gneiss I-1 Hornblende-Biotie Gneiss" - Shear Zons у* Strike s nd dip of foliation - ----Inferred Boundary -Major Road - Minor Road Setllement Figure 2: Geological map of Alaguntan area. Calc-silicate gneiss occurs parallel to the marble bodies and quartzite.They are Dark grey in colour, medium grained and foliated. Mineralogical constituent from XRD indicates it is composed mainly of dolomite (50 %], trem-olite (26 %], quartz (2 %], calcite (10 %] with minor amounts of magnesian spinel and graphite 2 % (Figures 3, 4, Table 1). The marble occurs in the western part of the study area. It occurs as lensoid bodies up to 2 000 m along the strike, 500 m wide and it crops out about 500 m wide around Alaguntan village. Color varieties ranges from pure white found at the southern part (Figure 5) and light to grey colour which occurs in the northern part of the occurrence. The colour variation may be due to the presence of tremolite and the magnesian spinel in places. The grain sizes vary from fine grain to medium grained (1-2 mm]. From XRD analysis, the marble is dominant-ly dolomite (95.4 %) with minor amount (below 3 %) of quartz, calcite and tremolite, while magnesian spinel, as trace mineral is less than 1 % (Table l). The association of marble with 'S' type granitoids and gneisses of metasediments (grey-wacke) origin suggests that the gneisses were reworked from ancient sedimentary sequences, as earlier suggested by [11] for the Burum marble in central Nigeria. The location of the marble at the eastern fringe of Iseyin - Oyan belt suggests that they are relict inliers of carbonate rich and epicontinental transgressive, silicic, arenaceous sequences. These were metamorphosed during a later tectono-meta-morphic cycle and accompanied by shearing/ mylonitisation probably in the Pan African, resulting in the final formation of carbonate sequences. The mineralogical composition shows that the marble is mainly dolomite (average 95.4 % up to 96.5 %) with minor amount (below 3 %) of calcite, colemanite, tremolite, actinolite, and quartz while the calc silicate associated with the marble contains dolomite (50 %), calcite (2.5 %), tremolite (19 %), quartz (25 %) magnesian spinel (1.8 %) and graphite 1.5 %) (Table 1). Samples of marble contain average MgO 23.08 % and CaO 32.01 %. Average silica (SiO2) content is 2.81 %. The average of alkalis: NaO, K2O and Al2O3 are all lower than 0.1 % while Fe2O3 content is slightly greater than 0.1 % but not more than 0.4 % (Table 2). TiO2, P2 05 and Cr2O5 were not detected in any of the samples. Ti, P and Cr oxides have staining influences (Ofulume, 1993), and the absence in the samples account for relatively high whiteness of the marble. These analytical results are comparable to values for other Precambrian marbles of Nigeria [2, 12, 13] and those for Shapfell, United Kingdom [14] (Tables 3, 4, 5). Trace element Pb, Zn, Ni, As, all have the average values: (3, 14, 3, 3) X 10-6 respectively. Sr value though significant at 41 x 10-6 is not considered high enough for sample coloration influences [4]. For economic and industrial raw material consideration purposes, these trace elements values are below deleterious levels. The plot of Molar ratio Mg2+/Ca2+ against temperature [15] Figure 6, reveals that the temperature of dolomitising solution in Alaguntan marbles may have been around 70 oC revealing a dolomitisation at shallow depth with low for-mational pressure. Plot of salinity against molar ratio Mg2+/Ca2+ also show salinity of formation water at 20 000 x 10-6 (Figure 7). This is much higher than fresh water average of 1 000 x 10-6, but less than average sea water (35 000 x 10-6) suggesting dolomitisation was facilitated by mixture of sea and fresh water. This agrees with the earlier suggestion of [15] that dolomitisation can occur at admixtures of 30-40 % sea water and 60-70 % fresh water. Carbon and Oxygen isotope content determination of 4 marble samples carried out at the act labs in Ontario, Canada reveal that 513C values range from -0.8-3.9 %o while 5180 range from 0.8 % to -8.2 %. These values suggest diage-netic equilibration with meteoric water and it is consistent with the fact that the formation water have dilution of sea by fresh water [16]. These stable isotope values are also consistent with values for Burum marble of the same litho-logic position and presumably the same genetic environment [2, 4] and Saxone basin carbonates, Germany [17]. These values are also comparable with values for carbonates that have undergone appreciable diagenesis in the presence of oxidizing organic matter and release of CO2 [16]. Figure 3: XRD dlffractometerpattern of Alaguntan marble (Sample 1). о НИИ kW Pf—i м к: К кип К л м йТШ, ris......ЖЕ; T ^ Figure 4: XRD diffractogram pattern of rus. "-i"**-^' Alaguntan marble (Sample 2). Table 1: Mineralogical composition of Alaguntan marble from XRD results Mineral, w/% 12 3 Dolomite 94.24 96.91 95.92 Calcite_120_-_- Quartz_-_0.54 0.35 Colemanite_1.20 2.55 2.59 Tremolite 1.35 - 1.14 Marble Usefulness evaluation Economic and industrial raw material usefulness was carried out in relation to such industries as agriculture (agronomic], metallurgy, construction, chemicals and environmental, materials (like fillers and extenders]. Construction: Marble is one of the oldest building materials and is only predated by mud and stone [18]. It is presently widely used in aggregates for soil stabilisation, mansory and as ornamental stones where it is polished into decorative slabs. General requirements are w(CaO + MgO] content above 95 % and w(CO2] < 50 %, compressive strength > 20 MPa, tensile strength > 7 MPa [19]. In term of finess, it must leave a residue not more than 5 % of 75 цт. Alaguntan marble meets these specifications and could thus be used as road stabilisers, ornamental ЯШШ [ \ Figure 5: Showing the Alaguntan white marble. Table 2: Chemical analytical results of the major oxides of Alaguntan raw marbles samples Oxides, 123456789 w/% 10 Range Average SiO2 1.56 1.58 2.93 5.56 1.89 4.69 2.74 2.52 1.51 3.15 1.51- 3.15 2.81 AI2O3 0.10 0.05 0.10 0.04 0.07 0.07 0.03 0.13 0.04 0.02 0.03- 0.13 0.07 ^A 0.13 0.10 0.11 0.21 0.24 0.24 0.19 0.07 0.10 0.16 0.10- 0.24 0.15 MgO 23.50 23.50 23.14 22.74 23.15 22.99 22.98 23.25 23.22 22.53 22.37- 23.50 23.20 CaO 33.12 32.96 31.83 21.17 31.52 31.52 32.12 32.43 32.36 32.24 30.79- 33.12 32.16 Na20 0.03 0.04 0.02 0.04 0.01 0.08 0.01 0.02 0.04 0.04 0.01- 0.08 0.03 K2O 0.03 0.02 0.01 0.01 ND 0.02 ND 0.02 0.02 ND 0.01- 0.03 0.02 MnO 0.01 0.01 0.04 0.03 0.04 0.03 0.03 ND 0.01 0.04 0.01- 0.04 0..03 LOI 41.1 41.1 41.4 39.8 42.5 39.9 41.5 41.2 42.3 35.9 35.9- 41.5 41.15 Sum (%) 99.61 99.61 99.60 99.61 99.61 99.60 99.60 99.62 99.61 99.59 99.60- 99.62 99.61 Table 3: Chemical analytical results of the trace element of Alaguntan raw marble samples Trace element (x 10-6) 10 Range Average Ba 10 5 3 2 3 4 3 3 5 3 2-10 4.1 Sr 40.5 40.4 34.9 48.5 41.7 50.1 54.6 28.2 30.1 42.6 28.2-54.6 41.26 U 0.2 0.2 0.4 0.4 0.3 0.4 0.6 0.4 0.2 0.3 0.2-0.6 0.34 Zr 1.3 1.9 1.6 0.6 1.2 1.3 1.3 1.1 1.1 0.5 0.5-1.9 1.19 Y 0.5 0.5 0.6 0.4 0.7 0.5 0.5 0.2 0.2 0.3 0.2-0.7 0.44 La 0.3 0.4 0.8 0.5 0.8 0.5 0.3 0.2 0.8 0.3 0.2-0.8 0.49 Ce 0.6 0.5 1.4 0.6 1.0 1.0 0.6 0.5 0.6 0.3 0.4-1.0 0.71 Pr 0.09 0.05 0.12 0.06 0.10 0.07 0.04 0.04 0.03 0.02 0.03-0.12 0.06 Pb 1.6 2.0 5.7 3.5 4.6 3.7 3.2 2.5 2.9 5.5 1.6-5.7 3.41 Zn 2 3 6 29 7 19 40 5 7 21 2-40 13.9 Ni 2.0 2.3 5.0 2.5 3.5 3.4 3.0 1.9 2.2 2.3 1.9-5.9 2.81 1 2 3 4 5 6 7 8 9 Table 4: Average chemical analytical results of Alaguntan marble and some marble deposit and lime products in Nigeria and the world. Oxides w/% 10 11 Si02 2.81 0.49 Tr 3.81 3.51 0.43 1.45 3.47 1.18 1.94 3.5 AlÄ 0.07 0.02 0.02 0.16 0.03 0.06 0.02 1.00 0.08 0.21 0.11 Fe2°3 0.15 0.06 0.06 0.15 0.05 0.02 0.05 0.21 0.07 0.12 0.04 Mn0 0.03 0.03 0.03 0.01 0.03 0.03 0.03 N. a. 0.03 0.01 N. a. Mg0 23.20 20.70 26.85 20.75 33.25 0.58 0.85 2.23 1.75 2.20 2.18 Ca0 32.16 28.94 38.29 31.03 59.17 54.17 95.35 51.29 53.64 52.5 51.69 Na20 0.03 0.01 0.01 0.05 N. a. 0.03 0.03 N. a. 0.01 0.02 0.92 K20 0.02 0.01 0.01 O.12 N. a. 0.06 0.03 N. a. 0.02 0.17 0.26 Ti02 ND ND ND 0.17 0.03 0.01 0.03 N. a. N. a. 0.06 N. a. P205 ND 0.03 0.03 0.05 1.63 LOI 41.15 34.73 43.56 43.81 2.12 41.53 41.6 41.97 Total 99.61 99.88 99.87 99.16 1. Alaguntan marble | 2. Igbetti marble (Emofurieta et al, 1995) | 3. Igbetti lime (Emofurieta et al, 1995) | 4. Burum marble (Elueze and Okunlola, 2003) | 5. Burum lime (Elueze and Okunlola, 2003) | 6 . Jakura marble (Elueze and Okunlola, 2003) | 7. Jakura lime (Elueze and Okunlola, 2003) | 8. Ukpilla marble (GSN Report No 1192) | 9. Ososo marble (Emofurieta, 1995) | 10. Shapfell marble ( Dowrie et al, 1982) | 11. South Korean marble ( DPR ) | ND Not detected | Tr Traces Table 5: Chemical analytical results of the calc silicate gneiss Oxides, w/% Element (x 10-6) SiO2 Al2O3 Fe2O3 MgO CaO NaO K2O TiO2 MnO P2O5 LOI Sum 10.34 0.03 0.16 22.27 30.79 0.02 0.01 ND 0.04 0.02 35.9 99.64 Ba Sr Zr La Ce Pr Pb Zn Ni As 30.9 0.2 0.1 0.2 0.3 0.4 0.04 5.5 2.3 3.0 Table 6: Physical properties of the Alaguntan raw marble samples Effective porosity n = 10 0.51-0.76 n = 10 0.64 Hardness (Mohs scale) 3.0 3.0 Bulk density g/cm3 2.65-2.67 2.66 Specific gravity 2.85-2.86 2.86 Compressive strength (MPa) 87.53-92.72 90.12 Shear strength (MPa) 13.62-15.10 14.36 pH 8.4-8.6 8.5 201 о 'M а E 45- SO-iO- ti t ti 6 OS 0. IS ! 10 IZ « 1 Mg*,/ Cai cJ i «f Figure 6: Molar ratio of calcium and magnesium required for dolomitisation of calcite as a function of temperature (Modified after HardieI15!). Figure 7: Relationship between total salinity, Mg/Ca ratio and origin of dolomite. (After I15!). Alaguntan Marble plots at 200 ppm salinity (0.008 x 300 dilution of sea water). stones and building blocks considering the values of the compressive strength, (90.12 MPa] and shear strength of 14.36 MPa (Table 6, 7]. Agricultural (soil acidity neutralizer): Results of agronomic tests (Table 8] have shown that the addition of the pulverised (below x^m] marble samples to an acid soil samples at intervals for 8 weeks reduced the soil acidity (Table 8] pH of interstitial water rose from 5.9 to 7.5 after 8 weeks. Organic matter content also increased to 12.31 from 11.70, base saturation show slight increase, while the available nutrient of N, P, K, Na, Ca, Mg, Fe, Mn, Zn, Cu, all show relative increases in their values from the original sample values. Alaguntan marble thus has the potential of being useful in ameliorating soil acidity. Metallurgy: Raw marble and their lime products have been found to be very useful in the metallurgy industry. The largest application is for fluxing steel[19, 20]. Requirement for metallurgical lime include (Ca,Mg)O, or w(CaO) > 50 %, high reactivity, low w(SiO2) (1-1.5 %], and low w(SO3] (0.05-1 %). Also, (Ca,Mg)CO3 or w(CaCO3) > 95 %. Alaguntan marble meets these specifications and therefore is useful as steel fluxes. Another metallurgical application of lime is production of refractory lime. This is used for lining open hearths. The requirements are similar to those of fluxes except for the less stringent SiO2 requirement (2-4 %]. Alaguntan marble can thus also be useful for production of refractory lime as seen from the chemical analytical results. Chemicals production manufacture: Among the largest uses of raw marble and their lime products is the production of sodium compounds such as sodium carbonate, sodium hydrogen carbonate, and sodium hydroxide by the Solvay (or ammonium soda] process. The basic requirement is a total carbonate w(CaCO3 + MgCO3] content greater than 70 % or lime/ dolomite (CaO,/CaMgO content of > 80 %. Alaguntan deposit also meet these requirements. In the manufacture of calcium carbide, an important source of acetylene, quicklime is Table 7: Physical properties of Alaguntan marble compared with other marble samples 1 2 3 4 5 6 7 8 9 10 Effective porosity 0.69 0.65 0.68 0.62 0.68 0.65 0.67 n. a. 0.64 Hardness (Mohs scale) 3.0 3.0 3.0 3.0 3.0 3.0 n. a. 3.0 n. a. 3.0 Bulk density 2.76 2.65 2.67 2.65 2.65 2.65 2.61 2.66 Specific gravity 2.73 2.70 2.70 2.71 2.73 2.68 2.71 2.73 2.75 2.86 Compression strength 90.48 95.52 92.83 n. a. 90.81 n. a. 90.5 88.2 n. a. 90.12 Tensile strength 3.87 3.92 3.81 n. a. 3.21 n. a. 6.5 4.52 n. a. n. a. pH 8.38 8.5 8.3 8.1 8.35 n. a. 8.11 8.5 8.6 8.6 Oil absorption (ml/100) n. a. 18.0 18.0 19.20 18.40 18.71 n. a. 20.15 n. a. n. a. Colour n. a. 82.0 83.0 80.0 80.0 92.8 n. a. 91.7 n. a. n. a. 1. Igbetti | 2. Jakura | 3. Burum | 4. Shapfell | 5. Cheetor | 6. British whiting | 7. Muro marble | 8. Indiana marble | 9. Ososo marble | 10. Alaguntan marble Source 1-9: (Elueze and Okunlola, 2003) Table 8: Agronomical properties of Alaguntan marble Treatment pH Organic matter g/kg CEC Base saturation % N g/kg P mg/kg K ^ Na cmol/kg Ca Mg Fe Mn Zn mg/kg mg/kg Cu OS 5.9 11.70 4.64 95.69 1.21 3.38 0.77 1.31 1.40 0.96 116.00 140.00 6.50 2.35 SA 5.9 11.70 4.64 95.69 1.21 3.38 0.77 1.31 1.40 0.96 116.00 140.00 6.50 2.35 A1 7.3 12.10 5.81 95.70 1.27 3.79 0.83 1.53 2.16 1.04 117.50 142.0 6.93 2.41 A2 7.5 12.31 6.88 95.74 1.34 3.86 0.98 1.71 2.36 1.53 119.00 144.00 6.94 2.41 OS = Original soil sample | SA = Soil + Alaguntan marble | A1 = Soil + Alaguntan marble after 4 weeks | A2 = Soil + Alaguntan marble after 8 weeks | CEC = Cation Exchange Capacity mixed with coke and heated in electric furnac- Environmental: es to 2 000 °C. Molten carbide is removed from Crushed and milled marble and their lime the furnaces and crushed upon solidifying. products have found application for environ- It is then ground for use. High calcium lime mental purposes [1]. This can be used for waste (w(CaO] = 90 %] / low w(P) (< 0.02 %) and water treatment and water softening. Lime re- w(Mg] < 0.5 % are required. Marble samples duces bicarbonate hardness. The requirement from the study area do not meet this require- include w(CaO) > 65 %, high alkalinity which ment because of higher than acceptable MgO makes it free from acid insolubles and toxic content. Also, in the production of cement, the heavy metals like Cd, Pb, Ag, Zn and Cr thereby major requirement are w(MgO) < 3 %, lime sat- having pH > 10, w(MgO) < 2 %, w(SiO2) < 0.01 uration factor (L. S. F.) 66-102 %, and hydraulic and absence of Co. Alaguntan marble has high modulus (H. M.) 1.7-2.0 %. The marble deposit w(MgO) and w(SiO2) > 0.01, therefore cannot is not suitable because of too high w(MgO) con- be used as a calcite lime but meets the specifi- tent of 23.20 %. cation for dolime manufacture. Table 9: Summary of usefulness potentials and specification for Alaguntan marble. Industry General requirements Suitability 1. Metallurgy a. Fluxes in steel b. Refractory lime (Ca, Mg)CO3 or w(CaCO3 ) > 95 % w(SiO2) = (1-1.5) % w(SiO^ = (0.05-1) % Same as in fluxes but SiO2 allowed 2-4 % Alaguntan marble is suitable because of its high silica content. Alaguntan marble is suitable. 2. Construction Compressive strength > 20 MPa Shear strength > 7 % ( ASTM, 1976) The deposit is suitable. 3. Chemicals a. Sodium compounds b. Calcium carbide c. Pesticides d. Bleaches CaO, (Ca,Mg) w(O) > 70 % w(CaO) > 90 %, w(P) < 0.02 % w(Mg) < 0,5 % w(SiO) < 1.2 % w(Fe203) < 0.5 % w(CaC03) > 90 % w(CaO) > 80 %, w(SiO2) < 2 % The deposits is suitable. Not suitable due to high magnesium content. Suitable. Not suitable due to high magnesium content. 4. Agriculture a. Soil liming pH > 8, w(SO3) = 2 % Agronomical test carried out revealed its suitability. Fillers and extenders: Mineral filler are inert materials incorporated into different compounds to accomplish a variety of final result such as modification of physical characteristics, colour, opacity hardness, impact strength, surface texture, viscosity, heat conductivity, reduction in cost of production and many other applications. Extender pigment is necessary in all types of coating in paint industry. This keeps the relatively more expensive pigment material volume to a minimum without affecting paint performance. For suitability for paint, requirement is w(CaCO3) > 95 %, w(MgCO3) = 2 %, w(SiO2) = 0.5 %, w(Fe2O3) = 0.05 %, w(Al2O3) = 0.30 % while for rubber is w(CaCO3) > 95 %, CaO, free CO2, w(MgO) = 0.02 %, Fe2O3, Al2O3, SiO2 must be in traces only. Alaguntan marble does not meet the above purposes because it has higher MgCO3 content. Conclusions The Alaguntan lensoidal marble body which occur for about 2.5 km along the strike within granite gneiss, subparallel to quartzite and calc silicates in Alaguntan village, southwestern, Nigeria, is of the dolomitic mineral composition with Mg/Ca 0.72). The SiO2 content is low compared to similar marble bodies in Nigeria and elsewhere. K2O, Na2O, MnO2, Al2O3 are all low, Fe2O3 marginally high while TiO2 is undetectable like some other marble deposit. Physical and mechanical test for the raw marble samples such as effective porosity, specific gravity, compressive and tensile strength in combination with chemical composition revealed their suitability as raw material in metallurgical, construction, chemical and agricultural industries, Table 9. Recommendations The study has been able to unravel the geological setting, compositional features and usefulness of the marble. Appropriate drilling programme should be designed and carried should be applied in order to quantify the reserve. Also, further work should be done on the calcined product of the marble. References [1] Boyton, S. (1980): Chemistry and Technology of limestone. John Wiley and Sons Inc. New York, 300 p. [2] Elueze, A. A., Okunlola, O. A. (2003): The compositional features and industrial appraisal of the metamorphosed carbonate rocks of Burum and Jakura area Central Nigeria. Mineral Wealth; 128, pp. 41-54. [3] Annor, A. E., Olobaniyi, S. B., Muche, A. (1996): A note on the geology of Isanlu in the Egbe-Isanlu schist belt, S.W. Nigeria. J. Min. Geol.; 32 (1), pp. 47-52. [4] Okunlola, O. A. (2001): Geological and compositional investigation of Precambrian marble bodies and associated rocks in the Burum and Jakura areas, Nigeria. Ph. D Thesis, University of Ibadan, 250 p. [5] Kennedy, W. P. (1964): The influence of the basement structure on the evolution of the coastal (Mesozoic and Tertiary basins of Africa). In D.C. Ion (Editor ), Salt basins around Africa). Inst. Petroleum; pp 7-16. [6] Rahaman, M. A. (1976): Review ofthe Basement geology of Nigeria. In Kogbe, C. A. (Ed) Geology of Nigeria. Elizabethan Publishing Co. Surulere, Lagos, 120 p. [7] Odeyemi, I. B. (1976): Preliminary report on the field relationship of Basement Complex around Igarra. Mid-western Nigeria. In C. A. Kogbe (Ed), Geology of Nigeria. Elizabethan Publishing Co., Lagos, pp. 59-64. [8] Muotoh, E. O. G., Oluyide, P. O., Okoro, A. U., Mogbo, O. E. (1988): The Muro hills banded iron formation GSN. Annotated technical reports; 1358, pp.15-25. [9] Rahaman, M. A. (1988): Recent advances in the study of the Basement complex of Nigeria. In Oluyide P.O. (Ed.). Precambrian Geology of Nigeria. GSN Journ.; pp. 241-256. [10] Ekwueme. B. N., Shing, R. (1987): Occurences, Geochemistry and Geochronology of mafic - ultramafic rocks in Obudu Plateau S. E. Nigeria in Srivasta R. K. and Chadta, R. (Eds) Magmatism relation to diverse tectonic settings. Res.; 34, pp. 269-289. [11] Okunlola, O. A., Oluyide, P. O (2009): Lithostructural, Compositional features and Industrial potentials of Pre Cambrian Carbonate deposits of the Federal Capital Territory, Nigeria. Records ofthe Nigerian Geological Survey Agency; 12, pp. 1-15. [12] Ofulume, A. B. (1992): The Jakura Marble as a filler/ extender in paints and plastic industries. J. Min. Geol; 27 (2), pp. 187-193. [13] Emofurieta, W. O., Ekuajeni, V. O. (1995): Lime products and economic aspects of Igbeti, Ososo and Jakura marble deposits in southwestern Nigeria. J. Min. geol.; 31 (1), pp. 89-99. [14] Dowrie, D. G, Walden, I., John F. (1982): Modern lime burning plant at Shapfell quarry. Management and products report; pp. 163-171. [15] Hardie, K. (1987): Stable isotope geochemistry. Springer Verlag. Berlin, 205 p. [16] Hoefs (1997): Stable isotope geochemistry. Springer Berlin-Heidelberg New York, 195 p. [17] Ihenyen, A. E. (1992): Geochemistry as a tool in identification of variations in depositional energy levels of carbonate rocks. Journal of Mining and Geology; 28 (2), pp. 369-375. [18] O' Driscoll. (1988): Burnt Lime / dolime - seeking market green industrial mineral AIME. 22, pp. 1-10. [19] American standard for testing materials (ASTM) (1976): Standard methods for physical testing of quicklime, hydrated lime and limestone. C-1100-761, 15 p. [20] United States Bureau of Mines. (1990): Principles of source/reserve classification for minerals. USGS circular 813. 45 p. Instructions to Authors Navodila avtorjem RMZ - MATERIALS & GEOENVIRONMENT (RMZ - Materiali in geookolje) is a periodical publication with four issues per year (established in 1952 and renamed to RMZ - M&G in 1998). 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Introduction Materials and methods Results and discussion Conclusions Acknowledgements References The sources should be cited in the same order as they appear in the article. They should be numbered with numbers in square brackets. Sources should be cited according to the SIST ISO 690:1996 standards. Monograph: [1] Trček, B. (2001): Solute transport monitoring in the unsaturated zone of the karst aquifer by natural tracers. Ph. D. Thesis. Ljubljana: University of Ljubljana 2001; 125 p. Journal article: [2] Higashitani, K., Iseri, H., Okuhara, K., Hatade, S. (1995): Magnetic Effects on Zeta Potential and Diffu-sivity of Nonmagnetic Particles. Journal of Colloid and Interface Science, 172, pp. 383-388. Electronic source: CASREACT - Chemical reactions database [online]. Chemical Abstracts Service, 2000, renewed 2/15/2000 [cited 2/25/2000]. Available on: . Podatki o avtorjih Podatki o avtorjih naj vsebujejo imena in priimke avtorjev, naslov pripadajoče inštitucije ter elektronski naslov vodilnega avtorja. Izvleček Izvleček namena članka ter ključnih rezultatov z ugotovitvami naj obsega največ 180 besed. Izvleček je podan v angleškem in slovenskem jeziku. Ključne besede Seznam največ 5 ključnih besed (3-5) za pomoč pri indeksiranju ali iskanju. Ključne besede so podane v angleškem in slovenskem jeziku. Uvod Materiali in metode Rezultati in razprava Sklepi Zahvala Viri Uporabljane literaturne vire navajajte po vrstnem redu, kot se pojavljajo v prispevku. Označite jih s številkami v oglatem oklepaju. Literatura naj se navaja v skladu s standardom SIST ISO 690:1996. Monografija: [1] Trček, B. (2001): Solute transport monitoring in the unsaturated zone of the karst aquifer by natural tracers. doktorska disertacija. Ljubljana: Univerza v Ljubljani 2001; 125 str. Članek v reviji: [2] Higashitani, K., Iseri, H., Okuhara, K., Hatade, S. (1995): Magnetic Effects on Zeta Potential and Diffu-sivity of Nonmagnetic Particles. Journal of Colloid and Interface Science, 172, str. 383-388. Spletna stran: CASREACT - Chemical reactions database [online]. Chemical Abstracts Service, 2000, obnovljeno 15. 2. 2000 [citirano 25. 2. 2000]. Dostopno na svetovnem spletu: . Scientific articles, review papers, preliminary notes and professional papers are published in English. Only professional papers will exceptionally be published in Slovene. Annexes Annexes are images, spreadsheets, tables, and mathematical and chemical formulas. Annexes should be included in the text at the appropriate place, and they should also be submitted as a separate document, i.e. separated from the text in the article. Annexes should be originals, made in an electronic form (Microsoft Excel, Adobe Illustrator, Inkscape, AutoCad, etc.) and in .eps, .tif or .jpg format with a resolution of at least 300 dpi. The width of the annex should be at least 152 mm. They should be named the same as in the article (Figure 1, Table 1). The text in the annexes should be written in typeface Arial Regular (6 pt). The title of the image (also schemes, charts and graphs) should be indicated in the description of the image. When formatting spreadsheets and tables in text editors, tabs, and not spaces, should be used to separate columns. Each formula should have its number written in round brackets on its right side. References of the annexes in the text should be as follows: "Figure 1..." and not "as shown below:". This is due to the fact that for technical reasons the annex cannot always be placed at the exact specific place in the article. Manuscript Submission Contributions should be sent to the following e-mail address: rmz-mg@ntf.uni-lj.si. In case of submission on CD or USB flash drive, contributions can be sent by registered mail to the address of the editorial board: RMZ - Materials and Geoenvironment, Aškerčeva 12, 1000 Ljubljana, Slovenia. The contributions can also be handed in at the reception of the Faculty of Natural Sciences and Engineering (ground floor), Aškerčeva 12, 1000 Ljubljana, Slovenia with the heading "for RMZ - M&G". Znanstveni, pregledni in strokovni članki ter predhodne objave se objavijo v angleškem jeziku. Izjemoma se strokovni članek objavi v slovenskem jeziku. Priloge K prilogam prištevamo slikovno gradivo, preglednice in tabele ter matematične in kemijske formule. Priloge naj bodo vključene v besedilu, kjer se jim odredi okvirno mesto. Hkrati jih je potrebno priložiti tudi kot samostojno datoteko, ločeno od besedila v članku. Priloge morajo biti izvirne, narejene v računalniški obliki (Microsoft Excel, Adobe Illustrator, Inkscape, AutoCad...) in shranjene kot .eps, .tif ali .jpg v ločljivosti vsaj 300 dpi. Širina priloge naj bo najmanj 152 mm. Datoteke je potrebno poimenovati, tako kot so poimenovane v besedilu (Slika 1, Preglednica 1). Za besedilo v prilogi naj bo uporabljena pisava Arial navadna različica (6 pt). Naslov slikovnega gradiva, sem prištevamo tudi sheme, grafikone in diagrame, naj bo podan v opisu slike. Pri urejevanju preglednic/tabel, v urejevalniku besedila, se za ločevanje stolpcev uporabijo tabulatorji in ne presledki. Vsaka formula naj ima zaporedno številko zapisano v okroglem oklepaju na desni strani. V besedilu se je potrebno sklicevati na prilogo na način: „Slika 1 ...", in ne „... kot je spodaj prikazano:" saj zaradi tehničnih razlogov priloge ni vedno mogoče postaviti na točno določeno mesto v članku. Oddaja članka Prispevke lahko pošljete po elektronski pošti na naslov rmz-mg@ntf.uni-lj.si. V primeru oddaje prispevka na CD- ali USB-mediju le-te pošljite priporočeno na naslov uredništva: RMZ - Materials and Geoenvironment, Aškerčeva 12, 1000 Ljubljana, Slovenija ali jih oddajte na: recepciji Naravoslovnotehniške fakultete (pritličje), Aškerčeva 12, 1000 Ljubljana, Slovenija s pripisom „za RMZ - M&G". The electronic medium should clearly be marked with the name of the leading author, the beginning of the title and the date of the submission to the Editorial Office of RMZ - M&G. Information on RMZ - M&G — Editor-in-Chief Assoc. Prof. Dr. Peter Fajfar Telephone: +386 1 200 04 51 E-mail address: peter.fajfar@omm.ntf.uni-lj.si — Secretary Ines Langerholc, Bachelor in Business Administration Telephone: +386 1 470 46 08 E-mail address: ines.langerholc@omm.ntf.uni-lj.si These instructions are valid from July 2013. Elektronski mediji morajo biti jasno označeni z imenom vsaj prvega avtorja, začetkom naslova in datumom izročitve uredništvu RMZ - M&G. Informacije o RMZ - M&G — urednik izr. prof. dr. Peter Fajfar Telefon: +386 1 200 04 51 E-poštni naslov: peter.fajfar@omm.ntf.uni-lj.si — tajnica Ines Langerholc, dipl. poslov. adm. Telefon: +386 1 470 46 08 E-poštni naslov: ines.langerholc@omm.ntf.uni-lj.si Navodila veljajo od julija 2013. Inženirska geologija Hidrogeologija Geomehanika Projektiranje Tehnologije za okolje ^ ISSN 1408-7073