© Author(s) 2022. CC Atribution 4.0 LicenseGEOLOGIJA 65/2, 177-216, Ljubljana 2022 https://doi.org/10.5474/geologija.2022.011 A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Pogled v izgubljeno zgornjetriasno in spodnjejursko arhitekturo pobočja in roba Dinarske karbonatne platforme Boštjan ROŽIČ1, Luka GALE1,2, Primož OPRČKAL3, Astrid ŠVARA4, Tomislav POPIT1, Lara KUNST6, †Dragica TURNŠEK5, Tea KOLAR-JURKOVŠEK2, Andrej ŠMUC1, Aljaž IVEKOVIČ7, Jan UDOVČ2 & David GERČAR1 1University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Geology, Aškerčeva 12, SI-1000 Ljubljana, Slovenia; e-mail: bostjan.rozic@ntf.uni-lj.si 2Geological Survey of Slovenia, Dimičeva ulica 14, SI-1000 Ljubljana, Slovenia 3Slovenian National Building and Civil Engineering Institute, Dimičeva ulica 12, SI-1000 Ljubljana, Slovenia 4Karst Research Institute, ZRC-SAZU, Titov trg 2, SI-6230 Postojna, Slovenia 5Ivan Rakovec Institute of Paleontology, ZRC-SAZU, Novi trg 2, SI-1000 Ljubljana, Slovenia 6ZOO Ljubljana, Večna pot 70, SI-1000 Ljubljana, Slovenia 7Odsek za nanostrukturne materiale, IJS, Jamova c. 39, 1000 Ljubljana, Slovenia Prejeto / Received 20. 4. 2022; Sprejeto / Accepted 19. 10. 2022; Objavljeno na spletu / Published online 21. 12. 2022 Key words: Slovenian Basin, Dinaric Carbonate Platform, Middle Jurassic, limestone breccia, debris-flow, Stra- tigraphy, Ponikve Breccia Ključne besede: Slovenski bazen, Dinarska karbonatna platforma, srednja jura, apnenčaste breče, drobirski tok, stratigrafija, Ponikvanska breča Abstract In the southernmost outcrops of the Slovenian Basin the Middle Jurassic coarse-grained limestone breccia (mega)beds are interstratified within a succession that is otherwise dominated by hemipelagites and distal turbidites. In this paper, these beds are described as the Ponikve Breccia Member of the Tolmin Formation. We provide descriptions of the studied sections with detailed geological maps and analysis of the breccia lithoclasts. From the latter, a non-outcropping margin of the Dinaric Carbonate Platform is reconstructed. In the Late Triassic the platform margin was characterized by a Dachstein-type marginal reef. After the end-Triassic extinction event, the platform architecture remained, but the reefs were replaced by sand shoals characterized by ooids. In the late Early Jurassic and/or early Middle Jurassic a slope area might have been dissected by normal faults and a step-like paleotopography was formed. In the Bajocian, during a period of major regional geodynamic perturbations, extensional or transtensional tectonic activity intensified and triggered the large- scale collapses of the Dinaric Carbonate Platform margin producing the limestone breccias described herein. This may in turn have caused a backstepping of the platform margin, as is evident from the occurrence of Late Jurassic marginal reefs that are installed directly above the Upper Triassic and Lower Jurassic inner platform successions. Izvleček V najjužnejših izdankih Slovenskega bazena se znotraj zaporedja, v katerem sicer prevladujejo hemipelagične kamnine in distalni turbiditi, pojavljajo (vele)plasti srednjejurske debelozrnate apnenčeve breče. V prispevku so te plasti opisane kot Ponikvanska breča in sicer kot člen Tolminske formacije. V opisu podajamo podroben opis proučenih profilov, vključujoč detajlne geološke karte in analizo litoklastov v breči. Iz slednjega je bilo možno rekonstruirati danes nerazgaljeni rob Dinarske karbonatne platforme. V poznem triasu je bil zanj značilen dachsteinski tip obrobnega grebena. Po triasno-jurskem izumrtju je arhitektura platforme sicer ostala enaka, vendar so grebene nadomestile peščene plitvine, za katere so značilni ooidi. V pozni spodnji juri in/ali zgodnji srednji juri je bilo območje pobočja razčlenjeno najverjetneje z normalnimi prelomi in nastala je stopničasta paleotopografija. V bajociju se je v času velikih regionalnih geodinamskih sprememb okrepila ekstenzijska ali transtenzijska tektonska aktivnost, ki je sprožila obsežne porušitve robnega dela Dinarske karbonatne platforme in nastale so tukaj opisane apnenčaste breče. To bi lahko povzročilo umik roba platforme, kar je razvidno iz pozicije zgornjejurskih obrobnih grebenov, ki se pojavljajo neposredno nad zgornjetriasnim in spodnjejurskim zaporedjem notranjega dela platforme. 178 Introduction The present-day geological structure of the territory of Slovenia is largely the result of the Late Cretaceous and post-Cretaceous tecton- ic shortening of the continental crust stemming from the Alpine orogenesis (Placer, 1999; Vrabec & Fodor, 2006). The nappe structure is especially evident in western Slovenia, where successions of three large Mesozoic paleogeographic units meet at the thrust faults (Fig. 1). Successions of the Triassic–Early Jurassic Julian Carbonate Plat- form (JCP hereinafter) and of the Early Jurassic– Late Cretaceous Julian High are preserved in the Krn Nappe, which forms most of the Julian Alps and the Kamnik-Savinja Alps (Placer, 1999). The Krn Nappe is in thrust-tectonic contact with the Tolmin Nappe to the south. The latter is charac- terised by deeper-marine successions deposited in the Slovenian Basin (SB hereinafter). Further south, the Tolmin Nappe is in turn thrusted over the Trnovo and Hrušica Nappes of the External Dinarides, consisting largely of shallow-marine carbonates of the Dinaric Carbonate Platform (DCP hereinafter) (Placer, 1999). According to Vlahović et al. (2005), the latter is a local synonym for the northern sector of the Southern Tethyan Megaplatform (Middle Triassic–Toarcian), and of the Adriatic Carbonate Platform (Toarcian–end of Cretaceous). The central unit of the Mesozoic topography is the SB, which lies between the Julian and Di- naric Carbonate platforms, which separates them but also provides a common sedimentary basin, acting as a sink for carbonate resediments shed from either of them. From the Early Jurassic to the beginning of Toarcian, the main source of carbonate shed into the SB was the JCP (Rožič, 2006, 2009). However, a dramatic decline in the proportion of resedimented limestone was re- corded during and after the Pliensbachian, when the JCP tectonically disintegrated and carbonate production ceased (Šmuc, 2005; Šmuc & Goričan, 2005; Rožič et al., 2014a). Fig. 1. a) Position of the studied area within the Europe; b) Present day distribution of three major Mesozoic paleogeographic units of the Southalpine-Dinaric transition: Julian Carbonate Platform (yellow without stripes), Dinaric Carbonate Platform (orange without stripes) and Slovenian Basin (areas with stripes). Upper Triassic (pink circles) and Upper Jurassic (blue circles) locations of marginal reefs are marked (compiled from Turnšek, 1997, Placer, 1999 and Rožič, 2016); c) Schematic sections of the Ponikve Breccia Member and Perbla section as a type locality of the Tolmin Formation (section localities are marked on Fig. 1b). B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 179 Younger, Toarcian to end-Jurassic deposits from the SB are instead dominated by hemipe- lagic sediments (Rožič, 2009). In the southern parts of the SB, however, sporadic resedimented limestones occur also in the Middle and Upper Jurassic, mainly in the form of calciturbidites less than a meter thick interbedded within radiolar- ite. They are interstratified in two distinct levels dated to Bajocian–Callovian and Kimmeridg- ian–lower Tithonian, respectively (Rožič & Popit, 2006; Rožič, 2009; Goričan et al., 2012). Instead of being derived from the “north”, these carbonate resediments originated in the “southerly” lying DCP. The extensive research of the southernmost outcrops of the SB showed that the lower (Bajo- cian–Callovian) resedimented limestones lateral- ly pass into successions of limestone megabreccias and subordinate calciturbidites up to 80 m thick (Fig. 1c). These resediments likely record the col- lapse of the DCP margin (Rožič et al., 2019). The composition of the resediments and their regional significance were recently presented by Rožič et al. (2019), but a more detailed analysis of the “lost” margin of the DCP was not includ- ed in such. The aims of this paper are thus: 1) to formalize breccia megabeds as a member of the Tolmin Formation and to describe its lateral oc- currences by contributing supplementary data on the local geological settings of the studied sec- tion, 2) to present a detailed clast analysis (mi- crofacies, biostratigraphy, paleoenvironment) of the recently studied sections (Rožič et al., 2019) and the Poljubinj and Zapoškar sections from older studies (Rožič, 2009), and 3) to reconstruct the Norian–Rhaetian, Lower Jurassic, and early Middle Jurassic margin stratigraphy of the DCP on the basis of clasts from megabreccias. Clast analysis also aims to answer two prom- inent regional questions. The first is the question of the structure and composition of the non-pre- served Norian–Rhaetian marginal reefs on the south-lying DCP. To the contrary, however, the Upper Jurassic marginal reefs of the DCP are well documented, but they are positioned far towards the inner parts of the platform. Our study at least partially answers the second question; namely, it elucidates the causes for the back-steeping of the DCP margin. Geological setting The SB is a large-scale (at least several tens of kilometres wide and extending W-E across the entire territory of present-day Slovenia) in- traplatform basin that shows continuous Ladin- ian to Maastrichtian deeper-marine sedimenta- tion that was bordered by the DCP to the “south” and the JCP to the “north” (present-day direc- tions). The latter disintegrated in the Pliensbachi- an and by the Bajocian turned into the subma- rine plateau called the Julian High (Buser, 1996; Šmuc, 2005; Šmuc & Rožič, 2010). The most con- tinuous succession of the SB is preserved in the Tolmin Nappe, which is the lowermost nappe of the eastern Southern Alps (Placer, 1999, 2008). In the eastern part of Slovenia, the equivalent deeper-marine successions are also found within the so-called Transition Zone between the Inter- nal and the External Dinarides, where they form nappes covering the shallow-marine successions of the DCP (Buser, 1996, 2010; Rožič, 2016). All of the studied sections represent the southernmost outcrops of the SB, distributed from the town of Tolmin in the west to the Mirna River Valley near the town of Sevnica in the east. Further to the east, the Mesozoic rocks are covered by the Neo- gene sediments of the Central Paratethys (Buser, 2010). The Ladinian succession of the SB is domi- nated by Pseudozilian beds, by volcanoclastic, clastic, and less frequently carbonate sediments. A similar succession is observed also in the Car- nian Amficlina beds, but with fewer volcanoclas- tics (Buser, 1989, 1996). In the southern part of the SB a large-scale platform collapse was doc- umented within the Carnian strata (Gale et al., 2016). After the reestablishment of continuous carbonate production on the DCP in the Norian, the SB became dominated by carbonates, mostly by Norian–Rhaetian Bača Dolomite (Buser, 1996), and locally limestones of the Slatnik Formation (Rožič et al., 2009; Gale et al, 2012). The Jurassic succession of the SB begins with the Hettangian–Pliensbachian Krikov Forma- tion, which is characterized by alternating hem- ipelagic and resedimented limestones. The latter dominate in the northern part of the SB, sug- gesting that the JCP was the main source of the resediments (Rožič, 2006, 2009). After the disin- tegration of the JCP, the SB became starved of (resedimented) carbonate, resulting in the dep- osition of the Toarcian marlstone-dominated Perbla Formation and Aalenian–lower Tithonian chert-dominated Tolmin Formation (Rožič, 2009; Goričan et al., 2012). Two levels of resediments occur within the Tolmin Formation in the south- ern and central parts of the SB, both shed from the DCP (Rožič & Popit, 2006; Rožič, 2009). The lower level, Bajocian–Bathonian (?Callovian) in age, is a distal equivalent of the limestone mega- breccias analysed herein (Rožič et al., 2019). A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope 180 The Jurassic–Cretaceous transition is marked by a sharp turn to the calcareous hemipelagic sedimentation, and Upper Tithonian–Berriassian Biancone-type limestone was deposited. Above, a poorly understood Valanginian–Barremian stratigraphic gap is present (Buser, 1996; Rožič et al., 2014a). Until the end of the Cretaceous the SB continuously received resedimented limestones from the DCP, but the nature of the hemipelag- ic sedimentation was changing. During the Ap- tian–Lower Cenomanian it was marl dominated (Lower Flyschoid formation). The Upper Cen- omanian–Turonian succession was character- ized by globotruncana-rich marly, varicoloured limestone (included in Lower Flyshoid formation by Cousin, 1981; also in our maps). Coniacian to Campanian is represented by Scaglia-type Volče Limestone, composed of gray hemipelagic lime- stones with cherts. The Maastrichtian Upper Fly- schoid formation is again marlstone dominated. It records a gradual transition to syn-orogen flysch sedimentation (Cousin, 1981; Buser, 1989, 1996). Methods A detailed geological mapping (scale 1: 5000) was performed in all investigated areas. Sedi- mentological sections were logged at 1: 100 or 1: 50 scales. Sections were sampled in dense inter- vals. Microfacies, corals, and foraminifera from the matrix and clasts of breccias were deter- mined for more than 300 thin sections using an optical polarizing microscope. Approximately 1500 clasts were analysed and divided into 25 groups according to their age and microfacies characteristics. Each group was compared with the Standard Microfacies Types (after Wilson; 1975; revised in Flügel; 2004). Classification of carbonates follows Dunham (1962), with mod- ifications by Embry and Klovan (1971). In the Lovriš section, several samples of conodonts were taken from bigger clasts. A standard tech- nique to recover conodonts was applied using di- luted acetic acid followed by heavy liquid sepa- ration. One sample was positive. In the Mrzli vrh, Lovriš, and Trnje sections cherts above, within, and below the limestone megabreccia unit were treated (with diluted 9 % hydrofluoric acid) for radiolarians but yielded no results. Formalization of the Ponikve Breccia Member of the Tolmin Formation Short description of the Tolmin Formation: The Tolmin Formation was defined by Rožič (2009) as an Aalenian–lower Tithonian unit composed of siliceous hemipelagites (for Perbla type sec- tion see Fig. 1c). It was divided into two members. The lower member, Aalenian–middle Bajocian in age, is composed of dark siliceous limestone and chert. The upper member (middle Bajocian–low- er Tithonian) comprises varicoloured radiolarite. Calciturbidites are interstratified within the pe- lagites in the southern and central parts of the SB in two levels. The lower level lies at the boundary between the lower and the upper member of the formation. These calciturbidites were approxi- mately dated to the Bajocian–Bathonian (?Call- ovian) and named Lower resedimented lime- stones. The upper level occurs in the uppermost part of the formation. It was dated to the upper Kimmeridgian–lower Tithonian and named the Upper resedimented limestones. Herein, we for- malize the limestone breccia megabeds as a new member of the Tolmin Formation, and represents the lateral, proximal variability of the Lower re- sedimented limestones. Name: Ponikve Breccia Member – It is thickest and best studied near the Ponikve Village on the Šentviška planota plateau. A similar term is also used for the Ponikve Klippe (that geologically comprises the Šentviška planota plateau), which is considered to represent the southernmost out- crops of the SB in western Slovenia. Previous work: The Ponikve Breccia Mem- ber is characteristic for the southernmost sec- tions of the SB succession. Breccias belonging to this member were previously mentioned by Cousin (1981) from localities near Tolmin, and by Ogorelec and Dozet (1997) from the vicinity of the town of Boštanj near the valley of the Mirna River. Breccias from the Poljubinj and Zapoškar sections were previously described in Rožič and Popit (2006), and Rožič (2009). Middle Jurassic Limestone breccia beds are reported from the Železniki area by Demšar (2016). A first detailed description of the unit was given by Rožič et al. (2019). Short definition: The Ponikve Breccia Mem- ber is usually several tens of meters thick. It can consist of a single or multiple, often amalgamated breccia beds. The member lies with a sharp ero- sional contact on older basinal formations, most often on the Hettangian–Pliensbachian Krikov Formation dominated by hemipelagic limestone with chert. At the top, the Ponikve Breccia mem- ber is conformably overlain by radiolarite or hemipelagic limestone with chert of the Tolmin Formation (Rožič., 2009; Rožič et al., 2014a). In some locations, the upper boundary is marked by a disconformity and younger formations (e.g. Lower Flyschoid formation) are overlain. B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 181 The thickness of the limestone breccia beds varies from meter-scale up to almost 80 m. Brec- cia is coarse grained and often contains me- ter-sized boulders. It consists of the Upper Trias- sic to Middle Jurassic basin, slope, and platform margin carbonate lithoclasts. Clasts are embed- ded in a micrite matrix with ooids and bioclasts (thin-shelled bivalves, crinoids). Breccia beds can be associated with calciturbidites, namely graded microbreccia and calcarenite. Exception- ally, hemipelagic sediments can be interstratified between thick breccia beds. Towards the central part of the basin this member laterally passes into the Lower resedimented limestones of the Tolmin Formation. Description of the type locality: The type lo- cality of the Ponikve Breccia Member is the Pod- brdo section (Fig. 2), located on the SW slopes of the Šentviška planota plateau (N46o08’06’’, E13o47’50’’), near the village of Ponikve. The sec- tion is named after the local name for a gorge and is not to be mistaken for the town of Podbrdo that lies in the Bača Valley. In this section, the Ponikve Breccia Member lies unconformably on the Krikov Formation dominated by hemipelagic limestone. It is 57.5 m thick and composed of amalgamated limestone breccia and subordinate calcarenitic beds. It be- gins with three limestone breccia beds (0.6, 2.3 and 8.4 m thick) that contain cm-sized litho- clasts. The succession continues with an inter- val almost 5 m thick dominated by fine-grained limestone breccia, often matrix supported (peb- bly calcarenite). Beds at the base of this inter- val are several tens of centimetres thick and be- come less expressed upwards. The thickest and coarsest bed follows, which reaches 37 meters and contains lithoclasts up to 10 m in size. The Ponikve Breccia Member ends with two graded fine-grained limestone breccia beds (1.3 m and 2.5 m thick, respectively) followed by three thin packstone beds. The Ponikve Breccia Member is overlain by si- liceous limestones and cherts of the Tolmin For- mation (for details see Rožič et al., 2014a). Two supplementary sections were logged in the vicin- ity of the type section (see below). Lateral variability: geological maps of the studied areas and description of the studied sections The Ponikve Breccia Mb is characteristic for the SB’s southernmost (most marginal) sections. So far, it is documented in areas of the sections presented herein. Additionally, Middle Jurassic breccia beds are mapped in the SB outcrops near the town of Železniki (Demšar, 2016) which is located between the Zapoškar and Škofja Loka sections, and near the town of Boštanj (Ogorelec & Dozet, 1997), close to the Mirna sections and the town of Celje (Sherman et al., 2022). The are- as of the studied sections are described in a west- to-east direction. Fig. 2. Detailed stratigraphic log of the Podbrdo section (type locality of the Ponikve Breccia Member) with positions of specific lithoclast types (for legend see Fig. 7). A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope 182 Mt. Mrzli vrh section The Mt. Mrzli vrh section was logged 3.5 km NW of the town of Tolmin where the western- most outcrops of the SB are preserved (Fig. 3). The succession is generally equal to the one de- scribed above in the Geological Setting chapter, but the Norian–Rhaetian is dominated by mas- sive dolomite overlain by basal limestone breccia of the Krikov Formation (for details see Rožič, et al., 2017). Some coarser grained calciturbidites (limestone microbreccia) occur within the Krik- ov Formation. The studied Middle Jurassic limestone mega- breccia occurs solely on the westernmost cliffs of the Mt Mrzli vrh where the section was logged (N46o12’43’’, E13o41’49’’). The contact with the un- derlying Krikov Formation is erosional. The Pon- ikve Breccia Member is 44 m thick and composed of a single graded bed with m-sized boulders, with cm-sized clasts at the topmost part of the bed (Fig. 4). It is overlain by approximately 15 m thick ra- diolarite of the Tolmin Formation and 4 m of the Biancone-type limestone. The overlying Lower Fig. 3. Geological maps of the Mrzli vrh, Poljubinj and Ponikve Plateau areas with locations of the studied sections. B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 183 Flyschoid formation is dominated by coarse grained resedimented limestones and forms an angular unconformity with underlying sedimen- tary rocks. Consequently, all Middle and Upper Jurassic beds are laterally eroded (towards east) and basal limestone breccias of the Lower Fly- schoid formation directly overlie the Krikov For- mation. In the mapped area, south of two prom- inent E–W trending faults, the Lower Flyschoid formation lies directly on the massive dolomite, and these faults are proposed to be reactivated paleofaults (for details see Rožič, 2005). Poljubinj section The Poljubinj section is located 1.5 km SE of the town of Tolmin, near the Poljubinj Vil- lage on the NW slopes of Mt. Kuk (N46o10’43’’, E13o45’28’’). Here, the overall succession shows more continuous and “classical” basinal succes- sion, which is displaced along several NW-SE and W-E oriented faults (Fig. 3). The Ponikve Breccia Member lies on top of the Perbla Formation (maybe even above a few basal beds of the Tolmin Formation). It is 11 m thick and contains dm-sized clasts (Fig. 4). It is followed by 9 m of thin- to medium-bedded ooidal calcarenites (calciturbidites) and fur- ther up by radiolarite of the Tolmin Formation (Rožič & Popit, 2006). The base of the latter was dated with radiolarians to the UAZ8 (middle Callovian to lower Oxfordian) (Goričan et al., 2012). Fig. 4. Detailed stratigraphic logs of the Mrzli Vrh, Poljubinj, and Zapoškar sections with positions of specific lithoclast types (for legend see Fig. 7). A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope 184 Fig. 5. Detailed stratigraphic logs of the Lovriš and Idrija pri Bači sections with positions of specific lithoclast types (for le- gend see Fig. 7). B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 185 Ponikve Klippe: Idrija pri Bači, Podbrdo, and Lovriš sections This area is located further to the SE (6 km from the town of Tolmin) on the NE slopes of the Šenviška planota plateau (Fig. 3). The area struc- turally belongs to the Ponikve Klippe, the only SB succession preserved south of the South-Al- pine thrust-front in all of western Slovenia (Bus- er, 1986; Placer, 1999). The contact with the un- derlying Trnovo Nappe of the External Dinarides is a thrust that is displaced by NW-SE strike-slip faults. The SB succession in the Ponikve Klippe is in an overturned position and shows quite typical SB development. The Ponikve Breccia Member forms a continuous belt along the southern slopes of the Šentviška planota plateau facing the Idrijca Riv- er Valley. Three sections were logged within this belt. In the Idrija pri Bači section (N46o08’26’’, E13o47’07’’) on the NW end of the belt, the Pon- ikve Breccia Member is 80 m thick and seeming- ly composed of a single breccia bed composed of m-sized boulders (Fig. 5). Towards the SE lies the Podbrdo section, described as the type-sec- tion above. The Lovriš section was logged on the SE end of the facies belt (N46o07’55’’, E13o48’14’’). The single limestone megabreccia bed was logged for 75 m, though the breccia unit may be even thicker, because the lower boundary is covered. This bed contains large limestone boulders that often exceed 10 m in diameter (Fig. 5). The described lateral changes in thickness and grain size of the member indicate that the topmost (thickest and coarsest) megabreccia bed is channelized into the underlying strata, often completely eroding preceding limestone breccia beds, which are preserved only in the Podbrdo section. The upper and lower boundaries of the Ponikve breccia are the same as in the type-lo- cality section. Zapoškar section The Zapoškar section is located 3.5 km north of town of Cerkno in the Zapoška grapa gorge that cuts the southern slopes of Mt. Porezen (N46o09’47’’, E13o58’27’’). The facies belt is con- tinuous and displaced solely by a minor NW–SE trending fault (Fig. 6). In the Zapoškar section, the succession of the Lower resedimented lime- stones of the Tolmin Formation is 25 m thick and composed of calcarenites and limestone breccia beds (Fig. 4). The latter are up to several meters thick and positioned in the central part of this succession and can be assigned also as the Pon- ikve Breccia Member. It lies on the siliceous lime- stone of the Lower Member of the Tolmin Forma- tion and is overlain by radiolarite of the Upper Member of the Tolmin Formation. Laterally, the Ponikve Breccia Member pinches out completely, and the two hemipelagic members of the Tolmin Formation are in direct contact. Škofja Loka: Podpurflca and Trnje sections The investigated area is constrained to a nar- row N–S extending belt of the SB outcrops, which starts approximately 1.5 km west of Škofja Lo- ka’s old town and extends for several km towards the north. The area is characterized by a rather complicated tectonic structure (Fig. 6). In a rela- tively small area three nappes (thrust sheets) are recognized. The lowermost is the Trnovo Nappe composed of the DCP succession ranging from Upper Triassic Dachstein Limestone down to the Palaeozoic basement rocks, whereas the upper two consist of the SB successions. In the middle thrust-sheet, the Carnian to mid-Cretaceous SB successions are found. It is composed of two distinctly diverse successions that exhibit major differences in the Jurassic part of the succession. The thrust sheet starts with shale/marlstone-dominated Amficlina beds which in the uppermost part contain an interval of thin-bedded micritic limestone several tens of meters thick, which is known in older liter- ature as Škofja Loka limestone (Ramovš, 1994). Upwards, it is followed by Norian–Rhaetian Bača Dolomite dominated by bedded dolomite with chert nodules, but in the Norian part thick dolomite-chert breccia beds are present and ac- companied by synsedimentary faults (Oprčkal et al., 2012). Upwards, through the cherty interval it passes into the Krikov Formation (named Van- covec limestone in Demšar, 2016) and the thin (10 m) Perbla Formation (here we notice that in the field it is often impossible to distinguish be- tween the micritic limestones of the Krikov For- mation and those from Amficlina beds). The Ponikve Breccia Member is slightly channelized and reaches approximately 50 m in thickness (Fig. 7). It was logged in a Podpulfr- ca section along the road between the villages of Podpurflca and Gabrovo (N46o09’31’’, E14o17’24’’). It is composed (often indistinctly) of amalga- mated beds of limestone (mega)breccia and subordinate calcarenite beds. Bed thicknesses vary from tens-of-centimetres to almost 10 m. The upper part of the member was additionally logged in a supplementary section located along the main road between Škofja Loka and Cerkno (N46o09’12’’, E14o17’25’’). The Ponikve Breccia A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope 186 Fig. 6. Geological maps of the Škofja Loka, Zapoškar and Mirna River areas with locations of the studied sections. B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 187A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Fig. 7. Detailed stratigraphic logs of the Škofja Loka area: Podpurflca and Trnje sections with positions of specific lithoclast types. 188 Member is unconformably overlain by the mid- Cretaceous Lower Flyschoid formation. The upper member of the Tolmin Formation, as well as the Biancone-type limestone, were eroded in this area. In the same thrust-sheet a specific, fault-iso- lated succession is found on the Dešna hill in the southern part of the mapped area (Figs. 1 and 6). The major part of the hill is composed of Bača Dolomite rich in dolomite breccia. It is overlain, after a long stratigraphic gap, by a thin interval of alternating radiolarite and marlstones (Up- per member of the Tolmin Formation). These are overlain by Biancone-type limestone followed by the Lower Flyschoid formation. In the structurally highest thrust sheet, lo- cated north of the Selška Sora River and Trnje Village, the succession is more continuous. Here the Ponikve Breccia Member overlies the Perb- la Formation and reaches almost 60 m in thick- ness (Fig. 7). It is composed of two thick beds (20 and 38 m), separated by a laterally discontinu- ous interval of reddish radiolarite (alternative- ly it could be a large chert lithoclast) up to 2 m thick. Both breccia beds show normal grading in the uppermost parts. The Ponikve Breccia Member is followed by a succession of red and green radiolarite some 30 m thick. Upwards, however, another 20 m- thick graded limestone megabreccia bed occurs, whose composition re- sembles the main interval. Both limestone mega- breccia intervals were logged in the Trnje sec- tion on the northern slopes of the Mala Roven hill (N46o10’57’’, E14o17’03’’). Upsection, another 20 m of red-violet radiolarite is found, which is followed by 40 m of the Biancone-type limestone. The contact between the Biancone Limestone and the south-lying Lower Flyschoid formation is a north-dipping thrust fault. Thrust structures are further dissected by a dense network of generally N–S striking nor- mal faults that occasionally redirect towards a NW–SE strike. In this setting, the eastern blocks (closer to the Ljubljana Field) were downthrown. The structure may have originated in the tran- stensional wedge between two regional NW–SE oriented faults (Rožič et al., 2015). In the mapped area the greatest downward movements were along the contact with the southwestern fault (seen in SW edge of mapped area in Fig. 6), which caused a further tilting of tectonic blocks (in- cluding beds as well as thrust planes). The de- scribed southward tilting is responsible also for the atypical, slightly south-dipping thrust plane between the Trnovo Nappe (DCP succession) and the middle thrust-sheet (SB succession with Pod- pulfrca section). Mirna River Valley: Jelovec and Krvavi mort sections The studied area is situated in the Mirna River Valley, between the small villages of Ga- brje and Jelovec, approximately 6 km SW of the town of Sevnica (Fig. 6). The area is dominated by a Lower Flyschoid formation. This shale-rich formation was previously mapped as Ladinian beds, but during mapping nanoplankton as well as foraminifers (in calciturbidites) were found and determined the mid-Cretaceous age of this formation (Iveković, 2008). Jurassic beds out- crop in the central part of the valley in tecton- ic blocks separated by SWW–NEE and NW–SE striking faults. The Jurassic succession begins with the Krikov Formation, which is dominated by micritic limestones but contains few calci- turbidite (graded calcarenite) beds. It is uncon- formably overlain by a Ponikve Breccia Member Fig. 8. Detailed stratigraphic logs of the Mirna River area: Jelovec and Krvavi Mort sections with positions of specific litho- clast types (for legend see Fig. 7). B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 189A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope that is composed of a single limestone mega- breccia bed. In the Jelovec section, logged in a gorge near the eastern entrance of the Lepi Dob railway tunnel, north of the Trebnje–Sevnica regional road (N45o59’23’’, E15o13’43’’), the brec- cia bed is 10 m thick and graded (Fig. 8). The supplementary Krvavi Mort section was logged in the Krvavi Mort gorge south of the Trebnje– Sevnica regional road (N45o59’19’’, E15o14’07’’). In this section, the breccia bed is thicker (at least 14 m) with large clasts occurring also in the upper part of the bed. Upsection, the brec- cia is overlain with sharp contact (logged in the Jelovec section) by an interval of medium-bed- ded, graded calcarenites (calciturbidites) 8 m thick, which have not yielded age-diagnostic fossils. According to the composition, which is the same as the Upper resedimented limestones of the Tolmin Formation, these calcarenites could already be Late Jurassic in age. Above, the 35 m thick Biancone-type limestone outcrops. In the area studied herein, the interval between the Krikov Formation and the Biancone lime- stone therefore lacks the hemipelagic sediments of the Perbla and Tolmin formations, which are usually present in other sections. However, ra- diolarite was reported a few kilometres east by Ogorelec and Dozet (1997). Microfacies of the Ponikve Breccia Member The dominant lithology in the Ponikve breccia member is a limestone breccia, whereas in some sections calcarenites also occur. In this paper we focus on the clast- and matrix-analysis of the breccia beds (see below). Calcarenites are often graded grainstone/packstone composed of ooids, peloids, intraclasts, basinal clasts (mud-chips) and bioclasts, i.e. predominantly echinoderms. Other fossils are benthic foraminifers, bivalve, brachiopod and ostracod shells, gastropods, and bryozoans. With fining composition changes into packstone composed of pellets to peloids and bi- oclasts, predominantly echinoderms, calcified radiolarians, and rare benthic foraminifers (for details see Rožič & Popit, 2006; Rožič, 2009; Rožič et al., 2018). Composition of the limestone breccia matrix Apart from the Mt. Mrzli Vrh section, the composition of the breccia matrix is generally uniform in all studied sections. It is mostly pack- stone, locally grainstone, composed of grains that are believed to be generally contempora- neous with sedimentation. The matrix is locally dolomitized. The grain composition is variable within and between different sections. However, except for the Mt. Mrzli vrh section, coarse micritized oo- ids and small- to medium-sized radial ooids with peloids and bioclasts in their cores (foraminifers, gastropods, crinoids, ostracods, bivalves, etc.) are always present and often dominant. The pack- stone/grainstone exhibit bimodal distribution in the size of the grains (Fig. 9a). Other grains, such as intraclasts, peloids (pellets), aggregate grains (lumps) and diverse bioclasts are also present (Fig. 9b). The most common bioclasts are echino- derm fragments and foraminifers, among which the trocholinids dominate over textularids and lagenids. Fragments of thin-shelled bivalves are locally present. Other molluscs (bivalves, gastro- pods, and brachiopods) are very rare. Other rare bioclasts are corals, calcimicrobes, bryozoans, and microbially encrusted, completely recrystal- lized clasts (presumably recrystallization-prone bioclasts, such as chaetetids). Alongside the aforementioned grain types, on- coids were also observed. They are abundant in the lower part of the Podbrdo section and were documented in the Mirna Valley area (Krvavi Mort section), as well as in the Škofja Loka area (Podpulfrca section). The cores of the oncoids are either micritic or contain bioclasts, such as gastropods, bivalves, fragments of encrusting fo- raminifers, or calcimicrobes. In contrast to breccias in other sections, the matrix of breccias in the Mt. Mrzli vrh section is a fine-grained packstone with fragmented thin-shelled bivalves and other bioclasts, among which echinoderms and sponge spicules prevail. Pellets, phosphate, and glauconite grains occur sporadically, whereas micritized ooids are pres- ent, but very rare. Both at the Ponikve Klippe and at Mrzli vrh the matrix of the limestone megabreccia is most- ly dolomitized. Locally the dolomitization affects the micritic lithoclasts as well. The primary tex- ture and composition of the matrix are preserved only in the pebbly calcarenites of the lower part (from the 15th to the 20th metre-mark) of the Po- drbdo section (Ponikve Klippe) and partially in the uppermost part of the limestone megabreccia bed in the Mrzli vrh section. In addition to the above-mentioned allochems, the breccia matrix and calcarenites in all sections also contain sand-sized lithoclasts. Their compo- sition is identical to the composition of the larger clasts described in Table 1. Calcarenites over- lying the limestone megabreccia in the Pobrdbo and Jelovec sections show a distinct increase in 190 crinoid abundance. This turnover in composition is most apparent in the Jelovec section, in which the overlying beds could already be of Late Ju- rassic age. Age of the Ponikve Breccia Member Some age-diagnostic foraminifers are pres- ent in both the matrix of limestone megabreccia and in the calcarenites (packstone/grainstone). They are well preserved, predominantly isolated, or rarely occurring in the cores of radial ooids. Protopeneroplis striata Weynschenk (Fig. 9c) is the most omnipresent, with Andersenolina pa- lastiniensis Henson and Mesoendothyra croatica Gušić also important for biostratigraphy. In the Podbrdo section, Mesoendothyra croatica Gušić was found less than a metre above the limestone megabreccia unit in calciturbidite interstrati- fied in the overlying hemipelagites of the Tolmin Formation. The age-range of the limestone mega- breccia studied is thus Bajocian–lower Bathoni- an (cf. Velić, 2007). In previous studies, a sample of radiolarite which was taken 2.4 m above the Lower resedi- mented limestones of the Poljubinj section yield- ed age diagnostic radiolarian assemblages char- acteristic for a UAZ 8 (middle Callovian-early Oxfordian) (Goričan et al., 2012). In the Lovriš section a sample of radiolarite was taken 13 m above the limestone megabreccia unit and yield- Fig. 9. Matrix of the Ponikve breccia: a) predominant grains are ooids, in some beds large oncoids occur (sample pp21.5), b) other matrix grains are pellets, aggregate grains, and bioclasts such as echinoderms, filaments, etc (sample KM4.1), c) age diagnostic Protopeneroplis striata Weynschenk occurs as isolated grain within the matrix (sample KM8.1). Fig. 10. T1 (a-c), T2 (d,e), and T3 (f, g) type lithoclasts: a) bioclastic wacke/packstone with echinoderms, foraminifera, fila- ments and unrecognisable bioclastic debris (sample LK2-54.5), b) slightly dolomitized bioclastic wackestone with echino- derms, filaments, ammonites and unrecognisable fossil debris (could belong to LJ4 clast type) (sample 338), c) Stromataxis structure within bioclastic wackestone (sample LK2-71.7), d) pelletal bioclastic packstone with Duostominidae formaninifera (sample 325), e) partly washed (corroded) matrix of the packstone with pellets, intraclasts, bivalve shell and foraminifera (Triasina hantkeni, Aulotortus sp.) (sample M65), f) pelletal intra/bioclastic grainstone with Duostominidae formaninifera (sample 337), g) intra/bioclastic grainstone with Galeanella tollmanni foraminifera and rare ooids. B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 191A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Fig. 10 192 ed UAZ 9-10 (middle to late Oxfordian to early Kimmeridgian) assemblage (Rožič et al., 2014a). Further basin-ward, the Lower resedimented limestone of the Tolmin Formation (which repre- sents a distal equivalent of the limestone mega- breccias presented herein) occur as calciturbidit- ic beds between radiolarite. Cherts just above the two lowermost calciturbiditic beds were dated to UAZ 4 (upper Bajocian). Cherts close to the up- permost beds were dated to the UAZ 8-10 (middle Callovian–early Kimmeridgian) (Goričan et al., 2012). Compiling the available data, we conclude that major resedimentation events occurred within a relatively short interval between the Bajocian and early Bathonian. However, it is possible that some large-scale collapses occurred also later during the Middle Jurassic. This is evident par- ticularly in the Trnje section, in which a thick ra- diolarite interval is interstratified between two limestone breccia megabeds. Clast analysis Clasts from breccias of the Ponikve Breccia Member are divided into 25 microfacies types (Table 1). As mentioned above, the composition of clasts in calcarenites corresponds to the clasts in breccias. The age of 14 microfacies types was de- termined. Six microfacies types are Late Trias- sic in age, and for most, we could narrow the age to the Norian–Rhaetian. Four microfacies types were assigned to the Early Jurassic, and four to the Middle Jurassic. The exact age for clasts be- longing to the remaining 11 microfacies types could not be determined. Below we provide some basic descriptions; for further details see Table 1. The first microfacies type (T1) from the Up- per Triassic clasts is a bioclastic wackestone, which also contains deep-water fauna (Figs. 10a- c). The second microfacies type (T2) is a pelletal bioclastic packstone (often partly washed) with abundant foraminifers (Figs. 10d, e). The third microfacies type (T3) is a grainstone similar in composition to the previous microfacies type, but contains large amount of intraclasts, and in some clasts also cortoids (Figs. 10f, g). Microfacies types T2 and T3 are believed to originate in sand shoals and in transition to the lagoon, but they may also come from the reef area (they are often observed as sediment fills between reef frames of boundstone clasts). The fourth microfacies type (T4) is a bioclastic rudstone with bioclasts made of reef-building organisms (Figs. 11a-c), and a similar fifth microfacies (T5) also contains reef lithoclasts (Figs. 11d-f). These two microfacies types could represent forereef sediments, or an inter-reef breccia. The last Triassic microfacies type (T6) is a typical reef boundstone with corals and calcisponges (stromatoporoids) as the main framebuilders (Fig. 12). The first Lower Jurassic microfacies type (LJ1) is a grainstone similar to the third Trias- sic microfacies type (T3) but contains less bio- clasts and additional ooids and aggregate grains. Grains of this microfacies type generally show less recrystallization (Figs. 13a-d). The second microfacies type (LJ2) is an ooidal grainstone, which in some clasts passes into a microfaceis of the previous group (Figs. 13d-f). Both microfaci- es types (LJ1 and LJ2) are believed to originate from sand shoals, the first one closer to the tran- sition with the lagoon. The third microfacies type (LJ3) is a crinoid-dominated grainstone (Figs. 14a, b), which in some clasts passes into a bio- clastic wackestone (microfacies type LJ4) com- posed of diverse bioclasts revealing open-marine conditions (Figs. 14c-f). This clast microfacies type is similar in composition to Triassic bioclas- tic limestone (T1) but generally contains more sponge spicules. Middle Jurassic clasts are divided into 4 mi- crofacies types. First is an ooidal packstone/ wackestone (MJ1) with a variable amount of ooids (Figs. 15a, b). Namely, in some packstone clasts ooids are dominant, while in others only sporadic ooids are found in a wackestone com- posed of pelagic fossils. Lithoclasts showing a transition from both end-members are present. The next two microfacies types are found only in the Mirna sections. The first of these two (MJ2) is a crinoidal limestone rich in lithoclasts (other- wise similar to LJ3) (Fig. 15c). The same is char- acteristic for the next microfacies type (MJ3), which in composition closely resembles older bio- clastic limestones (T1 and LJ4 microfacies types) but also contains quite an abundance of litho- clasts (Figs. 15d, e). The last Middle Jurassic clast microfacies type (MJ4) is a mudstone/wackestone Fig. 11. T4 (a-c), T5 (d-f) type lithoclasts: a) rudstone composed of diverse bioclasts (often encrusted by microbial laminae) deriving from the reef area (sample pp50.2), b) Calcisponge (left) and a microbial grain (right) as large grains of the bioclastic rudstone (sample pp50.2), c) foraminifera (Duostominidae and Galeanella tollmanni) and other reef debris as smaller grains of the bioclastic rudstone (sample pp52.0), d) reefal litho/bioclastic rudstone additionally contain lithoclasts (sample LK2 72.2), e) peloidal packstone lithoclasts with Galeanella tollmanni and bivalve fragments (sample LK2 57.2), f) a coral fragment (sample pp 57.6). B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 193A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Fig. 11 194 Fig. 12. T6 type lithoclasts: a) coral boundstone with pelletal packstone with corrosive voids infilling a space between coralli- tes (sample 315D), b) Recrystallized frame building calcisponges with encrustations of microbialites, foraminifera and serpu- lids (sample pp37), c) coral with microbial crust and peletal/bioclastic grainstone matrix between corallites (sample pp57.3), d) calcisponge with voids filled with peletal packstone (sample JE42.2), e) Baccanella sp sp and microbial mound (sample LK2 4.8). with pelagic fossils (Fig. 15f). Herein we note that age of this clast group was assigned due to the presence of planktonic foraminifers (cf. Caron & Homewood 1983; Tappan & Loeblich 1988; Dar- ling et al. 1997). These foraminifers, however, do not occur in all clasts and large amount of these clasts could also be older. The age of 11 microfacies types could not be univocally determined. The first such microfaci- es type (UD1) is common in almost all sections. It is a pelletal packstone that probably originated from a great variety of environments (Fig. 16a). Namely, in some clasts fenestrae were observed, while in others we noticed sponge spicules and thin-shelled bivalves (filaments) indicating open marine conditions. These clasts are likely of variable age. Similar microfacies was observed within the reef-frame of the boundstone clasts (T6) and furthermore, from one such clast we re- trieved upper Norian (Sevatian) to lower Rhaetian B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 195A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Fig. 13. LJ1 (a-d), and LJ2 (d-f) type lithoclasts: a) grainstone with pellets, intraclasts, micrite rimmed bioclasts (corto- ids) and foraminifer Orbitopsella sp. (O) (sample 327), b) grainstone with intraclasts, peloids, aggregate grains (lumps), and Siphovalvolina sp. (encircled) (sample JE34.4), c) partly washed packstone lithoclasts with intraclasts, pellets, and fragments of calcareous algae and coral Phacelophyllia termieri (P); mudstone clast (lower left) and ooidal matrix (sample pp19.6), d) transitional LJ1-LJ2 lithoclast in dolomitized matrix with intraclasts, ooid-dominated and foraminifera Reophax sp. fora- minifera, which agglutinated ooids (encircled) (sample pp5.2), e) grainstone with ooids, peloids, intraclasts and bioclasts, and chert clast (UD11) to the left (crossed polars) (sample KM12), f) partly washed packstone with ooids and pellets as dominant grains (sample pp5.2). conodonts. On the other hand, they can contain coarse laminas rich in ooids and intraclasts that are typical for first two Lower Jurassic microfa- cies types (LJ1, and LJ2). The next microfacies type (UD2) is a wackestone with coarse intra- clasts (also some ooids and pellets), which origi- nated in a quiet environment probably adjacent to the high-energy conditions (Fig. 16b). The third microfacies type (UD3) is a fine-grained and well-sorted packstone with pellets and bioclasts (Fig. 16c). It probably represents clasts of erod- ed calciturbidites. The next three microfacies 196 Fig. 14. LJ3 (a, b), and LJ4 (c-f) type lithoclasts: a) crinoidal grainstone with intraclasts, a dolomitized lithoclast (D), belemni- te (Be) and bivalve shell (Bs) (sample pp21.05), b) crinoidal grainstone with wackestone litho/intraclasts, and foraminifer Involutina liassica (encirceled) (sample KM4.1), c) packstone with echinoderms (crinoids), filaments and ostracods (sample JE37.4), d) wackestone with bivalve shell, sponge spicules, echinoderms and ostracods (sample LK2-74.2), e) wackestone with echinoderms, sponge spicules and foraminifera (sample LK2-74.2), f) floatstone with ammonites, filaments and crinoids (sample KM10). types represent sediments from an open-shelf or slope environment. The first of these (UD4) is a wackestone composed of crinoids and ophthal- midiid foraminifers and small pellets (Fig. 16d). Next is a spiculite crinoidal packstone (UD5) (Fig. 16e), and last is a filament packstone/grain- stone (UD6) (Fig. 16f). The next microfacies type (UD7) is a packstone with coarse grained pellets that presumably originated from a lagoon (Fig. 16g). The Last four microfacies types do not bear certain information on sedimentary environ- ments and age. First of these (UD8) is an almost B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 197A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Fig. 15. MJ1 (a, b), MJ2 (c), MJ3 (d, e) and MJ4 (f) type lithoclasts: a) wackestone with superficial ooids, benthic and plankton foraminifer, filaments and unrecognisable bioclasts (sample pp5.3), b) lamina with abundant filaments and peloids (sample KM3), c) grainstone composed of echinoderms (crinoids) and pelletal/ooidal grainstone (G) and bio/intraclastic wackestone (W) lithoclasts (sample KM5), d) wackestone with crinoids, fenestral mudstone (F) lithoclast, unrecognisable bioslasts and benthic foraminifera with determined Protopenerolis striata (sample KM8), e) wackestone dominated by crinoids and ooids with fracture filled with dog-tooth rim cement and matrix of the breccia (sample KM5), f) hemipelagic wackestone with cal- cified radiolarian, filaments, plankton foraminifer and other bioclasts (sample KM0.1). pure mudstone. In some clasts, pelagic fossils in- dicate open-marine conditions. Next is a recrys- tallized limestone (UD9), which sporadically shows ghosts of large fossils such as bivalves and ammonites (Fig. 16h). In the Ponikve Klippe and Mrzli vrh sections dolomitization is present and some clasts are completely replaced by dolomite (UD10). Last microfacies type (UD11) are chert clasts. In some cases, they most certainly repre- sent replacement cherts, as they show relicts of the primary packstone, grainstone, and bound- stone texture. 198 Fig. 16. age-undetermined (UD) lithoclasts: a) pelletal packstone with subordinate bioclasts (UD1) (sample pp18.0), b) intra- clastic wackestone with ostracodes (UD2) (sample JE40.4), c) well sorted bioclastic/pelletal packstone (UD3) (sample KM0.1), d) wackestone composed predominantly of echinoderms (crinoids) and ophthalmidiid foraminifera (UD4) (sample M105), e) packstone dominated with sponge spicules, and subordinate crinoids, other unrecognisable bioclasts and peloids (UD 5) (sample KM8.1), f) heart-shaped lithoclasts of the filament grainstone (UD6) (sample pp5.5), g) packstone with anemuran pel- lets, intraclasts, pellets and micritized ooids and bioclasts (UD7) and mudstone (UD8) lithoclasts to the right (sample JE43.4), h) recrystallized floatstone (UD9) with ammonite (sample T2/5). B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 199A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Table 1. Detailed description of composition, biostratigraphy, and sedimentary environment of microfacies types (abbreviati- ons: M – mudstone, W – wackestone, P – packstone, G – grainstone, R – rudstone, F – floatstone, B – boundstone, D – dolostone, SMF – standard microfacies). AGE CLAST TYPE DESCRIPTION Upper Triassic T1 Bioclastic W Composition: medium-grained grains prevail; ehinoderms (crinoid osscicles, echinoid spines), fragmented large bivalves (exeptionally even cm-sized), thin-shelled bivalves, foraminifers (miliolids, lagenids, and no- dosarids), ostracods, amonites, rare bryozoans and peloids. Large intra/bioclasts can have crusts made from calcimicrobes and foraminifers). It can contain laminae of crinoidal G (wash-out sediment; T1/4) and stro- matactis (LK2-71.7). Age: upper Carnian – Rhaetian (PODBRDO: foraminifers Lencticulina sp., Decapoalina sp., Miliolipora cuvillieri Brönnimann & Zaninetti, LOVRIŠ: foraminifers Parvalamella friedli (Kristan-Tollmann), Aulotortus sinuosus Weynschenk, Aulotortus tumidus (Kristan-Tollmann)). SMF and environment: SMF 8 – open shelf. T2 Pelletal bioclastic P Composition: structure is fine-grained P that can be party washed. Some laminae are G or W containing the same type of grains: pellets (peloids) and bioclasts, predominantly diverse foraminifers. Other grains are intraclasts, echinoderms, ostracods (can be abundant is some clasts – pp4.6), bivalves, gastropods; dasycla- dacean algae, ?Thaumatoporella. Transition to G (type T3) was observed within the same clast (JE39.4, DM97, TR37.2). This facies is locally bioturbated and contains large scale disolution voids filled with crusts of bladed cements (DM63.5, DM71.5), geopetally filled stromatactis (325), rare oncoids (DM97) and isolated corals (TR32.5). Age: Norian-Rhaetian (PODBRDO: foraminifers Galeanella tollmanni (Kristan), Miliolipora cuvilli- eri Brönnimann & Zaninetti, Duostominidae, LOVRIŠ: foraminifers Galeanella tollmanni (Kristan), Decapoalina schaeferae (Zaninetti et al.), Alpinophragmium perforatum Flügel, MRZLI VRH: foramini- fers, Auloconus permodiscoides (Oberhauser), Parvalamella friedli (Kristan–Tollman), Aulotortus sinuo- sus Weynschenk, Aulotortus tumidus (Kristan-Tollman), Galeanella tollmanni (Kristan), Duostominidae, Duotaxis birmanica Bronnimann, Whittaker & Zaninetti, Triasina hantkeni Majzon, Agathammina au- stroalpina Kristan & Tollmann, Duostominidae Duotaxis sp., Ophthalamidium sp. and Variostoma helicta (Tappan), and microproblematica Thaumatoporella pavovesiculifera Raineri). Clasts containing Triasina hantkeni Majzon reveal Rhaetian age. ŠKOFJA LOKA-PODPURFLCA: Duostominidae., ŠKOFJA LOKA- TRNJE: Duotaxis sp., MIRNA: foraminifers Aulotortus sp. and Trochammina almtalensis Koehn-Zaninetti). SMF and environment: between SMF18-for and SMF 16; lagoon or sheltered areas within the reef. T3 Intra/ bioclastic pelletal G Composition: medium- to coarse-grained G, locally partly washed P; predominant grains are intraclasts, pellets and diverse bioclasts: fragmented bivalves (often in form of cortoids), foraminifers (miliolids, textu- larids, ...), echinoderms, rare gastropods, brachiopods, and grains composed of calcimicrobes (can form cores of few-mm large intraclasts), oncoids was also detected (337). One clast consists of pellets, abundant forami- nifers (predominantly Galeanella sp.), frequent small radial ooids, and an oncoid (LK2-41.8). Age: Middle to Upper Triassic, predominantly Norian-Rhaetian (PODBRDO: foraminifers: ?Duostominidae, Trochammina alpina Kristan–Tollmann, Trochammina jaunensis Brönnimann & Page, Aulotortus sinuosus Weynschenk; LOVRIŠ: foraminifer Galeanella tollmanni (Kristan), MRZLI VRH: foraminifers Auloconus permodiscoides (Oberhauser), Parvalamella friedli (Kristan–Tollman), Triasina hantkeni Majzon). Clasts containing Triasina hantkeni reveal Rhaetian age. ŠKOFJA LOKA-TRNJE: foraminifers Galeanella toll- manni (Kristan), Alpinophragmium perforatum Flügel, Duostominidae ŠKOFJA LOKA-PODPURFLCA: foraminifer Endoteba ex gr. controversa Vachard & Razgallah, MIRNA: foraminifer Galeanella tollmanni (Kristan). SMF and environment: SMF 11, sand shoals at the platfrom margin. T4 Bioclastic R Composition: structure passes from R to locally coarse-grained G: predominant grains are bioclasts: lar- ge grains are fragments of frame-builders: calcisponges, corals and calcimicrobes; other smaller bioclasts are echinoderms, foraminifers, fragmented bivalve shells, Tubiphytes, rare gastropods and dasycladacean algae. Other grains are intraclasts and pellets. Large grains can have microbial encrustations. Bioclasts in some clasts can be altered to cortoids. Age: Norian-Rhaetian (PODBRDO: foraminifers: Galeanella tollmanni (Kristan), Duostominidae, Reophax sp., Aulotortus sinuosus Weynchenk and Decapoalina schaeferae (Zaninetti, Altiner, Dager & Ducret); sponge: ?Cryptocoelia sp.; coral: Astraeomorpha pratzi Volz; MIRNA: foraminifers Galeanella tollmanni (Kristan), Duostominidae). SMF and environment: SMF11, SMF5 reworked reefal material within or on either side of the reef. T5 reefal litho/ bioclastic F/R Composition: There are two main constituents. The first are bioclasts of frame-building organisms up to a few mm in size, such as corals and calcisponges. Subordinate encrusters are calcimicrobes and foramini- fers. The second main constituent are lithoclasts of A) reefal limestones, including sponge/coral B with the interstices filled with intra/bioclastic pelletal P/G or with sparite; these clasts resamble microfacies T6, B) pelletal intra/bioclastic P/G (resembling clasts of micro- facies types T2 and/or T3), C) pelletal P (resembling clasts of microfacies type UD1), and less frequent D) coarse bioclastic limestone with fragmented bioclasts and intraclasts with echinoderms (resembling clasts of microfacies type T1). The space between large clasts is filled by coarse-crystaline cements (fibrous and dog-tooth rim cements, and drusy mosaic cements), less frequently by micrite. In the area of Škofja Loka (Trnje section) matrix contains echinoderms and sponge spicules. Age: Norian-Rhaetian (PODBRDO: foraminifers: Galeanella tollmanni (Kristan), Reophax rudis (Brady); Duostominidae; sponge ?Battaglia minor Senowbari-Daryan & Shaefer, MRZLI VRH: forami- nifer Decapoalina schaeferae (Zaninetti, Altiner, Dager & Ducret); ŠKOFJA LOKA-TRNJE: foramini- fers Decapoalina schaeferae (Zaninetti, Altiner, Dager & Ducret), Miliolipora cuvillieri Brönnimann & Zaninetti, Galeanella sp., Endotriada sp.). SMF and environment: SMF 6 fore- or intra-reef breccias. T6 B Composition: The frame is built by corals (mostly faceolid) and sponges (stromatoporoids, inozoan, subor- dinate chaetetid calcisponges), often encrusted by calcimicrobes and foraminifers, serpulids, in some clasts also by Thaumatoporella sp. Baccanella sp. was spotted. Frame-builders tend to be strongly recrystalized. Intergranular space is filled with coarse-crystaline cements (mostly fibrous rim and drusy mosaic or bladed cements), or intra/bioclastic pelletal P/G (closely resembling microfacies types T2 and T3, described above). Sediment can contain birds-eye fenestrae. Some clasts are strongly dolomitized, and some also silicified (TR44). Age: Norian-Rhaetian (PODBRDO: foraminifers: Galeanella tollmanni (Kristan), Duostominidae; Decapoalina schaeferae (Zaninetti, Altiner, Dager & Ducret), Miliolipora cuvillieri Brönnimann & Zaninetti; LOVRIŠ: foraminifers Endotriada tyrrhenica Vachard, Martini, Rettori & Zaninetti, Endotriada sp., Miliolipora sp., ŠKOFJA LOKA-TRNJE: Galeanella sp., MIRNA: foraminifer Alpinophragmium perfo- ratum Flügel, and microproblematica Bacinella irregularis Radojčić). SMF and environment: SMF7; marginal reefs. 200 AGE CLAST TYPE DESCRIPTION Lower Jurassic LJ1 Intra/ bioclastic pelletal G with aggregate grains and ooids Composition: medium to coarse-grained G, subordinate partly washed P; in composition similar to micro- facies type T3, but contains less fossils with the addition of aggregate grains (lumps) and ooids, whereas intaclasts tend to be irregularly shaped; some grains have micritic margins or encrustations. Oncoids were also detected. In one clast they form laminae of oncoidal R that separate microfacies LJ1 from ooidal G (LJ2). Oncoidal cores are formed of ?Thaumatoporella and calcimicrobes (JE41.4). Foraminifers are mostly textulariids. Some clasts contain laminae with large gastropods. In clasts with abundant aggregate gra- ins, bivalves, crinoids, calcimicrobic grains, ?Thaumatoporella, and cortoids were spotted (JE43.4). A clast containing a dasycladacean fragment was also documented, (pp19,7) and another with abundant cortoids and large bioclasts: bivalves, brachiopods, gastropods, dasycladacean algae, ?ammonite, and a foraminifer Orbitopsella sp. (327). Age: Lower Jurassic (PODBRDO: coral Phacelophyllia termieri Beauvais; IDRIJA PRI BAČI: forami- nifers ?Lituosepta recoarensis Cati, Orbitopsella sp., MRZLI VRH: foraminifer ?Siphovalvolina sp., ZAPOŠKAR: Duotaxis metula Kristan, ŠKOFJA LOKA-PODPURFLCA: ?Siphovalvolina sp., MIRNA: co- rals Rhabdophyllia phaceloida Beauvais, Thecactinastraea krimensis Turnšek, Funginella domeriensis Beauvais, foraminifers Involutina liassica Jones, ?Siphovalvulina sp.). In one clast in Podpurflca section, a Middle Jurassic foraminifer Nautiloculina was determined. SMF and environment: SMF 15 to SMF 17; platform margin sand shoals. LJ2 Ooidal G Composition: predominant grains are medium-sized, radial ooids, mostly with micritic cores, very subor- dinate bioclasts. Other grains are intraclasts, peloids, and bioclasts: echinoderms, fragmented mollusks and foraminifers (ophthalmidiid foraminifers, and Reophax sp.). In one clast a chaetetid grain was noted (2A-6). Some clasts are partly washed P and have bimodal grain-size distribution with large ooids and bi- oclasts (mostly crinoids) and small peloids (pellets). Some clasts are composed of fine-grained radial ooids and peloids/pellets (KM5). In one clast this facies passes into oncoidal R (JE41.4) that contains foraminifer Siphovalvulina sp. In one clast this facies passes to bioclastic limestone (J2). Age: Lower Jurassic (MIRNA: Involutina liassica Jones, Siphovalvulina sp.). SMF and environment: SMF 15; platform margin sand shoals. LJ3 Crinoidal G Composition: G, also subordinate P that can contain lithoclasts and fossils some mm in size. Predominant grains are crinoids (echinoderms), angular intraclasts, and sometimes pellets. Crinoids can contain micri- tic encrustations. Other grains are foraminifers (textulariids, lagenids, ophthalmidiid), bivalves (often fra- gmented), gastropods, ostracods. Grains some few mm in size are lithoclasts of bioclastic W (in facies similar to clast-type T1 and LJ4) and belemnites. In some clasts crinoids strongly predominate or even represent all the grains. These clasts can be often partly silicified. Age: Lower Jurassic (MIRNA: Involutina liassica Jones). SMF and environment: SMF 12-CRIN; open shelf/platform slope accumulation of crinoidal debris. LJ4 Bioclastic W Composition: grains are mainly medium-sized. Predominant grains are sponge spicules, echinoderms and ostracods. Other bioclasts are amonites, filaments, foraminifers (ophthalmidiids, lagenids, nodosarids, textularids). P and F textures also occurs. These clasts closely resemble type T1 and MJ3, but generally contain more sponge spicules. Without diagnostic fossils it is usually impossible to distinguish the three types. In clasts where it passes to ooidal G (JE35.4) it also contains medium-sized ooids with radial inner and tangential outer cortex (equal to those of ooidal G). Ooids were observed also in one sample (KM5) from the Mirna Valley. This microfacies can also pass to crinoidal G (T2/4). Age: Lower Jurassic (ŠKOFJA LOKA-PODPURFLCA: Involutina farinacciae Brönnimann & Koehn- Zaninetti, MIRNA: Involutina liassica Jones). SMF and environment: SMF 8 – open shelf. Middle Jurassic MJ1 Ooidal P/W Composition: fine- to medium-sized tangential and/or radial ooids, peloids (pellets), intraclasts and echi- noderms. Other bioclasts are bivalve fragments, foraminifers (lagenids, textularids), ostracods. Some clasts contain quite abundand thin-shelled bivalves (filaments), sponge spicules, calcispheres and/or radiolari- ans. Ammonites were detected. In the Mirna section, filament-rich clasts also contain planktic foraminifera (KM3.0) and clasts dominant by pellets and subordinate ooids (KM7.2). This microfacies locally passes into bioclastic M/W (microfacies UD5) within the same clast. Specific sub-type of this clasts group (pp14) is composed of alternating laminae of M and P/W with coarse- -grained micritized ooids and subordinate intraclasts and echinoderms. Ooid cores are micritic or bioclastic (gastropds, ostracods). Oncoids also appear. Age: ?Middle Jurassic (ŠKOFJA LOKA-PODPURFLCA: planktic foraminifers). SMF and environment: ?SMF15; structural inversion where grains typical of high-energy conditions are resedimented to low-energy, probably deeper water environment. MJ2 Lithoclastic crinoidal G Composition: coarse-grained G composed of echinoderms (mostly crinoids), micritic (intra)clasts, fragmen- ted brachiopods and bivalves, and foraminifers (ophthalmidiid foraminifers, lagenids, nodosarids, fra- gments of sessile foramininifers). Common are also lithoclasts: A) pelletal/intraclastic/ooidal G and P, B) W with radiolarians and filaments, C) fenestral M, D) spiculitic W, and E) bio/intraclastic W. Age: Middle Jurassic (MIRNA: Protopeneroplis sp.). SMF and environment: SMF 8 – open shelf, but close to source of lithoclasts. MJ3 Litho/ bioclastic W Composition: grains are medium- to coarse-grained W with microsparite matrix. Predominant grains are echinoderms (crinoids as well as orchin spines) and foraminifers (ophthalmidiid foraminifers, lagenids, no- dosarids). Other grains are micritic (intra)clasts, fragmented bivalves and brachiopod, ooids and ammonites also occur. These clasts closely resemble microfacies types T1 and J2 but contain more lagenid foraminifers and lithoclasts: A) pelletal ooidal G and P, B) W with radiolarians and filaments, and C) fenestral M. Matrix is microsparite. Without diagnostic fossils it is usually impossible to distinguish the three types. Age: Middle Jurassic (MIRNA: Protopeneroplis striata Weynschenck). SMF and environment: SMF 8 – open shelf. MJ4 Bioclastic (hemipelagic) M/W Composition: predominanly fine-grained W, sometimes with very rare grains (M). Grains are bioclasts, mostly thin-shelled bivalves, ostracods, and calcispheres and/or calcified radiolarians. Rare are lagenid foraminifers, small echinoderms, sponge spicules and other (unrecognisable) small debris. Amonites and gastropods were detected within such clast in the Mirna section (KM0.1, KM4.1), and planktic foraminifers (KM3.0). Tiny pellets are locally visible within matrix. Bioturbation and in one clast (LK2-57) also stroma- tactis were noticed. These clasts tend to be dolomitized. Age: ?; at least part of clasts are Middle Jurassic (MIRNA: Protoglobigerina sp.). SMF and environment: SMF3 pelagic limestone of the deep-water sedimentary environment (?mud-chips). B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 201A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope AGE CLAST TYPE DESCRIPTION Undeter- mined UD1 Pelletal P Composition: fine-grained P that can be partly washed and bioturbated. Predominant grains are pellets. Other are bioclasts, such as small foraminifera, ?calcispheres, and ostracods. Matrix is mostly microsparite. Some clasts contain sponge spicules and other filaments (KM13,4; KM14.4), the latter representing transi- tional facies to filament P/G (microfacies UD6). Rare clasts of this group can contain small fenestrae (pp18, KM8.1, JE39.4). When laminated, some coarses laminae contain intraclasts and ooids and probably represent transitional facies to ooidal G (JE43.4). Age: Large clast from the top of the Lovriš section yielded late Norian to early Rhaetian conodonts Norigondolella steinbergensis (Mosher) and Zieglerioconus rhaeticus Kozur and Mock, but this clast group is almost certainly also of Jurassic age, as in some clasts it contains laminae of ooidal limestone (for this reason we keep it among undetermined clasts). SMF and environment: SMF16 (21) or SMF2; low-energy environment, either restricted lagoon (with subae- rial exposure) or open shelf. UD2 Intraclastic W Composition: W with medium-sized intraclasts and pellets, micritized ooids were also detected. Some clasts contain ostracods, unrecognisable bioclastic debris, fenestrae, and large dissolution voids filled by blocky calcite (LK2-17.5; LK2-18.8). Age: ? SMF and environment: ?SMF; stuctural inversion, where grains typical for high-energy conditions are rese- dimented to a low-energy environment (either lagoon or deeper water). UD3 Bioclastic pelletal P Composition: fine-grained P, composed of bioclasts, such as echinoderms, fragmented bivalves (inclu- ding filaments), ostracods, calcispheres, foraminifers. Half the grains are pellets. Elongated grains are parallel-oriented. Age: ? SMF and environment: ?SMF4, presumably resedimented limestone (calciturbidite). UD4 Crinoidal foraminiferal W Composition: W that laterally pass to partly washed P. It is dominated by echinoderms, ophthalmidiid fo- raminifers (textularids and lagenids also occur) and small pellets. Rare grains are fragmented bivalves, brachiopods, ostracods and ooids. A subtype of this microfacies occurring in the Lovriš section is P, dominated by echinoderms and pellets. This subtype also contains rare foraminifers. (LK2-8.6, LK 2.8 and LK 12.5) Age: ? SMF and environment: SMF 12-CRIN; open shelf/platform slope accumulation of crinoidal debris. UD5 Spiculite crinoidal P Composition: fine-grained, bioturbated P, composed of sponge spicules and echinodermes. Other grains are foraminifers, ostracods, ?radiolarians, and pellets. Matrix can be recrystalized to microsparite. Some spi- cules are calcedonic. Age: ? SMF and environment: SMF 12-CRIN and SMF 2 open shelf/platform slope/basin floor. UD6 Filament P/G Composition: The first subtype is G, composed of accumulated filaments (thin-shelled bivalves) and very rare echinoderm fragments. Cement is drusy-mosaic cement (pp; 5.5; pp11.4). The second subtype is P, which is dominated by filaments, but can also contain echinoderms, peloids, foraminifers, and ammonites. Filaments can have thick rims of fibrous cements, mostly concentrated at one side of the shells (in clast within KM7.2 sample infiltration matrix postdates the cementation). One clast is densely packed P, where predominant filaments wrap around intraclasts, rare echinoderms and foraminifers (occurs in the Idrija pri Bači section in samples 354A; 354B). Age: ?Jurassic. SMF and environment: SMF 12-S open shelf/platform slope/basin floor accumulation of filaments. UD7 Coarse peloidal P Composition: coarse-grained P, composed of peloids and rare micritized oval bioclasts (presumambly dasycladacean algae), and intraclasts. Ostracods and small foraminifers were spotted. A sub-type was spotted (JE43.4): W/P with anemuran pellets, other grains are similar, but bivalve fragments, calcispheres and lagenid foraminifers additionally appear. Age: ? SMF and environment: SMF 16 restricted lagoon. UD8 M Composition: mostly pure M. It locally contains ostracods, foraminifers, or pelagic bioclasts (filaments, radi- olarians). The matrix is dense micrite, locally microsparite. Rare fenestrae (geopethally filled cavities) occur in few clasts. Some contain numerous fenestrae (T2/10). Age: ? SMF and environment: SMF23 and 21 or SMF3; restricted low-energy environment (restricted lagoon or anoxic basin). UD9 Recrystalized F Composition: strongly recrystalized F (or pure R) with still recognized large fossils, such as ammonites and bivalves (T2/6). Brachiopods and gastropods also occur in other clasts (LK2-16.5). Cements are dog-teeth rim cements, followed by coarsely crystalline bladed cements, and calcisiltite (crystal silt). A little amount of matrix clings to the fossil shells. It is P, composed of tiny pellets and rare ostracods. Age: ? SMF and environment: ? SMF 8 deep-water environment. UD10 D Composition: coarsely crystalline D. The primary texture is locally partly preserved. It is bioclastic M/W (microfacies type UD5), or B (microfacies type T5). Age: ?, some are probably dolomitized clasts of Norian-Rhaetian B. SMF and environment: ? dolomitization obscured information. Some were presumably reefal, others hemi- pelagic limestone. UD11 chert Composition: microcrystalline chert, locally with concentrated carbonate crystals (in laminae or in pa- tches). One clast laterally passes into B (microfacies T6), a different one into intra/bioclastic pelletal G (mi- crofacies T3). The primary composition of medium-grained P/G is locally recognizable. Silicification can be strong in B clasts (microfacies T6). Age: ? SMF and environment: mostly replacement chert (contains carbonate and passes into limestone). 202 Discussion Facies distribution of the Ponikve Breccia Member and corresponding Lower resediment- ed limestones of the SB indicates that the south- ern-lying DCP was a source area of the Middle Jurassic resedimented material. Namely, coarse and thick limestone breccia beds occur solely in the southernmost SB outcrops (structurally low- est nappe), become finer and thinner (in the form of calciturbiditic calcarenites) in the central part of the basin (central nappe), and are completely absent in the northern part of the SB (structur- ally highest nappe) (Figs. 17 and 18). Additional proof pointing to the source area is provided by the abundance of ooids within the breccia matrix and inside calciturbidites. As the DCP is the only known post-Aalenian active platform in this part of the Adria microplate (review in Vlahović et al., 2005), the DCP is considered the only possible source of these resediments. The clast- and matrix-analysis of the Lime- stone Breccia member therefore enables the re- construction of the non-outcropping DCP mar- gin from three distinct time periods. The Upper Triassic (Norian–Rhaetian) and Lower Jurassic reconstructions are based solely on the records retrieved from the clast analysis. For the Middle Jurassic reconstruction, the data from matrix- and clast analysis was combined, which consid- ered the age of the matrix to be contemporaneous with the sedimentation event of the breccia beds. The Upper Triassic: a reef-rimmed epeiric platform Epeiric platforms covering the tropical mar- gins of the Neotethys Ocean generally consist- ed of a wide tidal flat, a shallow lagoon, and a platform margin rimmed by reefs (Mandl, 2000; Bernecker, 2005). The tidal flat is stratigraph- ically represented by the Hauptdolomit (Glavni dolomit/Dolomia Principale/“Main Dolomite”), gradually passing into the bedded Dachstein limestone (Mandl, 2000; Bernecker, 2005; Kovács et al., 2011). Characteristic for these beds is the so-called Lofer cycle, comprising a thin brec- cia member, a laminated mudstone (intertidal stromatolite), and a biogenic wackestone and/ or floatstone with large megalodontid bivalves, gastropods, and locally corals (Fisher, 1964; Ogorelec & Rothe, 1993; Satterley, 1996; Ogore- lec & Buser, 1996; Haas, 2004; Samankassou & Enos, 2019). The marginal peri-reef belt has been recorded by Piller (1981), Wurm (1982), Haas et al. (2010), Gale et al. (2012), and Martindale et al. (2013), among others. The massive reef lime- stone is composed of interreef breccias and small patches of coral-sponge-solenoporacean algae reefs. Molluscs, benthic foraminifers, and dasy- cladacean algae are among the diverse bioclasts within sand-grained detritus (Wurm, 1982; Gale et al., 2013). The slope is characterised by calci- turbidites composed of grains derived from the top of the platform and its margin (Rožič et al., 2009; Gale, 2010; Gale et al., 2014). In the inte- rior of the platform small basins of the Kössen type, characterised by depositions of marlstone and limestone and a diminished diversity of ben- thic fauna came into existence during the Rhae- tian. Patch reefs developed at the rims or within these basins. Their composition is comparable to the composition of the marginal Dachstein-type reefs (Schäfer & Senowbari-Daryan, 1981; Kuss, 1983; Bernecker, 2005). In the inner parts of the platform, significantly more restricted basins already formed in the Norian. These basins are characterised by reduced oxygen levels, abnor- mal salinities and/or eutrophic conditions. Along their margins, small bioherms composed of ter- ebellid worms encrusted in microbiallite were present. (Cirilli et al., 1999; Iannace & Zamparel- li, 2002). Norian–Rhaetian Hauptdolomit and Dachstein limestone of the northern External Dinarides have been most intensively studied by Ogorelec and Rothe (1993). Both formations show charac- teristics of the internal part of the platform, with well-developed Lofer cycles. In the northern Ex- ternal Dinarides, the Dachstein-type reefs are not preserved (Buser et al., 1982; Turnšek, 1997). Six microfacies types from clasts (T1–T6) were attributed to the Late Triassic DCP. These clasts can reach the size of boulders. Boundstone with typical Norian–Rhaetian reef-dwelling fo- raminifers Galeanella, Decapoalina, Miliolipora and Alpinophragmium (see Gale, 2012) strongly suggest that the original margin of the DCP was rimmed by Dachstein-type reefs, which later col- lapsed into the SB together with Lower and Mid- dle Jurassic deposits (Fig. 17). Bioclastic rudstone (T4) and litho/bioclastic floatstone/rudstone are interpreted as reef breccia akin to lithoclas- tic rudstone Gale et al. (2013). The close affinity with the reef zone is supported by the abundance of framebuilders and reef-dwelling microbiota (e.g. Decapoalina, Miliolipora, Galeanella). Bio- clastic wackestone (T1), pelletal bioclastic pack- stone (T2), intra/bioclastic pelletal grainstone, and possibly also part of pelletal packstone (UD1) were also found in clasts within the litho/ bioclastic floatstone/rudstone (T5), some also in B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 203A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope boundstone (T6), and thus also likely deposited close to the margin of the platform. This is again supported by the presence of some microfossils. Bioclastic wackestone (T1) might originate in the open-shelf/slope area. The Lower Jurassic: a lagoon, rimmed by sand shoals Like the Upper Triassic, the outcropping Low- er Jurassic successions from the northern Ex- ternal Dinarides show facies associations char- acteristic for the inner platform developments. General Lower Jurassic successions from the northern Dinarides were described by Dozet and Strohmenger (2000), Črne and Goričan (2008), Miler and Pavšič (2008), Dozet (2009), Ogorelec (2011), and Gale and Kelemen (2017), among oth- ers. An unpublished thesis of Buser (1965) also provides a regional overview of Jurassic succes- sions from southern Slovenia. Lower Jurassic successions from other parts of the Dinarides were (among others) described by Dragičević and Velić (2002), Tišljar et al. (2002), Bucković (2006), Črne and Goričan (2008), Čadjenović et al. (2008), and Martinuš et al. (2012). Despite the biocalcification crisis at the Trias- sic/Jurassic boundary (e.g. Kiessling et al. 2007), a carbonate platform continued to exist (Fig. 17). During the Hettangian, carbonate deposition continued under peritidal conditions. Charac- teristically, laminae are not wrinkled, but pla- nar and smooth. During the Sinemurian and Pliensbachian, the topography of the platform gradually evolved from the epeiric, flat-topped platform into a platform, internally differentiat- ed into lagoon, marginal shoals, and ephemeral emergent areas (Buser & Debeljak, 1996; Gale and Kelemen, 2017). This, together with the re- covery and evolution of biota after the Triassic/ Jurassic boundary extinction, results in distinct differences in microfacies. A transgressive trend towards more subtidal conditions was noted in central Slovenia, where most of the Sinemurian part of the succession is represented by mudstone and wackestone, subordinately peloidal and oo- idal limestone. Oolithic and bioclastic-oolithic grainstone become predominant by the upper Sinemurian, and the facies association also in- cludes mudstone, peloid wackestone, bivalve floatstone and rudstone, and peloid grainstone. In the Pliensbachian, these facies are joined by common oncoid and bioclast floatstone and rud- stone, and lithiotid floatstone and rudstone (Gale and Kelemen, 2017). Buser and Debeljak (1996) envisioned the platform margin as dominated by ooidal and crinoidal shoals, and slope covered by breccias. The Ponikve Breccia Member contains an abundance of clasts that have been attributed to the Lower Jurassic, either based on foraminifers or their microfacies. The clast microfacies types LJ2 (ooidal grainstone) and LJ1 (intra/bioclastic pelletal grainstone) probably originate from the ooidal shoals and a more agitated part of the in- ternal lagoon, respectively. In contrast, the crinoidal grainstone (LJ3) and the bioclastic wackestone (LJ4) clasts derive from a deeper water sedimentary environment. Lower Jurassic crinoid/sponge spicule rich limestones are characteristic for diverse environments, such as the drowned platforms of the Eastern Alps and the Trandanubian Range (Böhm et al. 1999; Gawlick et al. 2009; Haas et al. 2014), but they also occur in slope settings (Scheibner and Reijmer, 1999; Blomeier and Reijmer, 2002; Me- rino-Tomé et al., 2012; Della Porta et al., 2014). Here we emphasise that such facies are also typi- cal for the Sedlo Formation, which originated on the JCP margin that experienced tectonic differ- ention and accelerated subsidence already in the Pliensbachian (Šmuc, 2005; Šmuc and Goričan, 2005; Praprotnik Kastelic et al., 2013; Rožič et al, 2014b; Valand et al., 2019). This subsidence of the JCP margin correlates to the initiation of a sec- ond rifting phase of the Alpine Tethys that is well recognized also in the rest of the Southern Alps (Berra et al., 2009; Masini et al., 2013) and led to the creation of a North Adriatic Basin located west of the DCP (Masetti et al., 2012). This extension must have influenced the northern DCP margin and potentially led to the partial reorganization of the DCP architecture. Namely, it could have created a fault dissected, step-like margin and slope, which would be reflected in a shift from the carbonate platform to the carbonate ramp ar- chitecture of the northernmost part of the DCP. Such depositional setting provided open marine conditions favourable for the creation of the de- scribed facies-types. Alternatively, the crinoidal limestone could also represent Toarcian facies originating from the drowned platform margin. During this stage, the succession of the DCP is characterised by thin-bedded micritic limestone and crinoidal-ooidal limestone, recording trans- gression which roughly coincides with the OAE (Vlahović et al., 2005; Črne and Goričan, 2008; Dozet, 2009; Sabatino et al, 2013). We note that coeval with Lithiotid evolution the re-establishment of marginal reefs is locally doc- umented for the late Lower Jurassic (Leinfelder 204 Fig. 17. Reconstrution of the Dinaric Carbonate Platform’s northern margin from late Late Triassic (Norian–Rhaetian) reefs, through early Early Jurassic ooidal sand shoals, Toarcian transgression and re-establishment of the carbonate production up to the early- and mid-Middle Jurassic onset of extensional/transtensional tectonics, which led to the collapse of the platform margin and deposition of the Ponikve breccia Member of the Tolmin Formation in the Slovenian basin. B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 205A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Fig. 18. Stratigraphic columns of the Dinaric Carbonate Platform, Slovenian Basin, and Julian Carbonate Platform with reconstructed (lost) margin of the Dinaric Carbonate Platform. Facies distribution of the Middle Jurassic resedimented li- mestones (including the Ponikve Breccia) indicate that the south-lying Dinaric Carbonate Platform was a carbonate material source area (compiled from Buser, 1986, 1996, Turnšek, 2007; Šmuc, 2005, Rožič, 2006, 2009; Rožič et al., 2014b; Kovač, 2016; time scale after Cohen et al., 2013; updated). 206 et al., 2002; Scheibner & Reijmer, 1999; Meri- no –Tomé et al., 2012; Della Porta et al., 2014). Local occurrence of coral patch reefs is known also from the Pliensbachian of the northern DCP (Turnšek & Košir 2000; Turnšek et al. 2003) with coral species corresponding to those determined in some Lower Jurassic grainstone lithoclasts (type LJ1; Podpurflca and Mirna sections). How- ever, we do not support the existence of barrier reefs on the DCP because: A) Lower Jurassic age was not determined for the boundstone (or relat- ed) clasts and B) all other (better preserved) plat- form margins from the Southern Alps (Clari and Masetti, 2002; Masetti et al, 2012; Francheschi et al., 2013) as well as the DCP are dominated by ooidal sand shoals (Tišljar et al, 2002; Črne & Goričan, 2008; Čadjenović et al., 2008). Platform-basin transition zone prior to Middle Jurassic collapses Breccia beds originated in the toe-of-slope and proximal basin plain environments. They sedimented as the result of debris flows and were a product of large-scale collapses of the DCP margin (for details see Rožič et al., 2019). Already within some sections presented herein, breccia beds are associated with turbidites, and towards the inner parts of the SB they pass completely into calcturbiditic layers (named Lower resedi- mented limestones) which occur within siliceous pelagites of the Tolmin Formation (Rožič, 2009, Goričan et al., 2012; Rožič et al., 2019). The abundance of ooids and associated shal- low-water grains (peloids, intraclasts, aggregate grains, oncoids and some bioclasts) in the matrix of the breccia and associated calciturbidites in- dicates that the gravity flows began at the DCP margin. Following the Toarcian deepening, the shallow water sedimentation gradually re-es- tablished on the margin and crinoid-rich ooidal limestones that pass upwards into pure ooidal limestone were deposited (Fig. 17) (Buser, 1996; Črne & Goričan, 2008; Miler & Pavšič 2008; Bus- er & Dozet 2009; Ogorelec 2011; Dozet & Ogorelec 2012). In addition, the breccia matrix contains deep- er-water bioclasts, most typically thin-shelled bivalves, whereas crinoids are also considered as predominantly deeper-water grains (see also be- low the discussion on Middle Jurassic lithoclasts). This indicates the incorporation of deeper-water (outer shelf/slope and basin) sediments into the debris-flows. In the Mrzli vrh section, ooids and associated shallow-water grains are almost en- tirely absent, while other grains (thin-shelled bi- valves, crinoids, sponge spicules, phosphate, and glauconite) point to initiation of this debris flow from the distal deep slope/open shelf area. Important information on the architecture of the platform-basin transitional area comes from lithoclasts that we have determined to be Middle Jurassic, and therefore contemporaneous with the sedimentation event. Ooidal packstone/ wackestone clasts (MJ1) originate from the outer shelf close to the sand shoals. This is indicated by the co-occurrence of ooids and pelagic deep- er-marine fauna. Such deposits are known from the Middle Jurassic successions on Mt. Matajur and Mt. Kobariški stol (Šmuc, 2012; Udovč, 2019; Rožič et al., 2022). Bio/lithoclastic limestones of the MJ2 and MJ3 lithoclasts were proposed to have deposited basin-wards on a step-like slope (Fig. 17). Such paleotopography must have been produced by active faulting, as indicated by the abundance and diversity of lithoclasts, which occur inside these microfacies types (MJ2 and MJ3 lithoclasts types). These “lithoclasts inside lithoclasts” are of shallow-, as well as of deeper-water origin and could be pre-Middle Jurassic or generally con- temporaneous with sedimentation of MJ2 and MJ3 lithoclasts types. It seems that their erosion may have been enhanced by the formation of es- carpments. The last type of Middle Jurassic lithoclasts is a hemipelagic limestone (MJ4). These lithoclasts originated with the debris-flow erosion of the contemporaneous, semi consolidated, hemipelag- ic (lower slope/basin) sediments and are there- fore interpreted as “mud-chips”. Information from lithoclasts of undetermined age The majority of the lithoclasts of undetermined age was sedimented in deeper-marine environ- ments. Pelletal packstone (UD1) and intraclastic wackestone (UD2) most probably deposited on the outer shelf. At least some of the UD1 clasts are Late Triassic in age, while some could be Ju- rassic. They were probably located between the typical marginal facies and slope environments similar to ooidal packstone/wackestone (MJ1). Crinoidal foraminiferal wackestone (UD4) and spiculite crinoidal packstone (UD5) correspond to similar crinoid rich clasts, which are typical for the outer shelf/slope environments in differ- ent time slices (T1, LJ3, LJ4, MJ2, MJ3). Filament packstone/grainstone (UD6), mud- stone (UD8), and bioclastic pelletal packstone (UD3) mostly originate from the erosion of slope B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 207A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope and basin sediments, the first two being hemipe- lagic, and the last resedimented limestones. Due to the absence of plankton foraminifers, they are considered Aalenian in age or older. Such facies are common in Lower Jurassic and Upper Trias- sic pelagites (Cousin 1981; Rožič 2009; Rožič et al. 2009, 2013; Gale et al., 2012, 2014). Therefore, debris flows of the Ponikve Breccia did not sole- ly erode the contemporaneous basinal sediments (MJ4), but also older hemipelagic strata. This is also evident from the stratigraphic position of the breccia megabeds that overlie the older basi- nal successions with a stratigraphic gap (mostly overlying the Hettangian–Pliensbachian Krikov Formation). We already mentioned the basinal succession of the Dešna Hill in the Škofja Loka area, where (Bajocian or younger) radiolarite of the Tolmin Formation directly overlie the Nori- an-Rhaetian Bača Dolomite (Fig. 5 in Rožič et al., 2019). During the sedimentation of the Ponikve Breccia megabeds this area was bypassed and was very likely deeply eroded by debris flows. Although shallow-water clasts predominant- ly originate from the margins of the DCP, some clasts indicate at least minor erosion of the plat- form interior. Such are coarse peloidal pack- stones (UD7), pelletal bioclastic packstones (T2), and partially also pelletal packstones (UD1). Due to diagenetic changes, such as recrystallization (UD9), dolomitization (UD10), and silicification (UD11), the origin of the last three lithoclast types is difficult to determine. The Middle Jurassic collapse of the Dinaric Carbonate Platform margin The Ponikve breccia originated with major collapses of the entire northern margin of the DCP (Fig. 17). This is evident from: A) breccia megabeds occur in an almost continuous belt from the westernmost outcrops of the SB near Tolmin, through the Škofja Loka area in cen- tral Slovenia, to the easternmost occurrences in the Mirna Valley, B) the extraordinary nature of the resedimentation events, with the large- scale debris-flow deposits representing a great contrast to the underlying and overlying succes- sions characterized by basin-plain (hemi)pela- gites, and C) clasts indicate deep erosion of the carbonate platform margin cutting down to the Upper Triassic reef limestone. The compilation of available biostratigraphic data indicates that a major part of these events happened in a rela- tively short time interval in the Bajocian and ear- ly Bathonian. Some large-scale resedimentation events post-dated the main collapse events also later (in the late Middle Jurassic). This is evident from the Trnje section in which a rather thick radiolarite succession is interstratified between breccia megabeds. We associate the formation of the breccia megabeds with the regional tectonic activity (Rožič et al., 2019). The initiation of these events coincides with the major mid-Middle Jurassic re- organisation of oceanic domains surrounding the Adria microplate (de Graciansky et al. 2011; Mas- ini et al. 2013; Schmid et al. 2020). Alpine Teth- ys (Piemont-Ligurian ocean) that was positioned to the west/northwest, moved from the syn-rift to the post-rift phase (oceanisation) during the Middle Jurassic (Chiari et al. 2000; Bill et al. 2001; Manatschal & Müntener 2009; de Gracian- sky et al. 2011; Ribes et al., 2019, 2020; Le Breton et al., 2021). Towards the east, the Neotethys do- main experienced the initiation of the intraoce- anic subduction dated as Aalenian to Oxfordian (Borojević Šoštarić et al. 2014; Schmid et al. 2020 and references therein). This was followed by the obduction of ophiolites onto the Adria margin, but the exact timing of the start of the obduction is still debated and varies from mid-Middle Ju- rassic (Gawlick et al. 2016; 2017a,b,c; 2018; Gawl- ick and Missoni, 2019, Bragin & Djerić, 2020), the latest Middle Jurassic (Bortolotti et al., 2013) to the Late Jurassic (Mikes et al. 2008; Schmid et al. 2008, 2020; Gallhofer et al. 2017). Paleogeographically, the transitional zone be- tween the DCP and the SB was located between the Piemont-Ligurian and the Neotethys oceans. For this reason, it must have been highly influ- enced by the described tectonic perturbations. The exact nature of the tectonic deformations at the transition zone is obscured by the Ceno- zoic South-Alpine tectonic overprint. However, an accelerated subsidence is documented in the deep-marine successions across the Southern Alps, including the SB (Bertotti et al. 1993; Mar- tire 1996; Martire et al. 2006; Šmuc 2005; Chi- ari et al. 2007; Rožič 2009; Šmuc & Rožič 2010; Goričan et al. 2012). Subsidence north of the DCP must have (re)activated normal faults along its northern margin, thus increasing the depth of the SB, enhancing the relief, and consequently pro- duced collapses of the platform northern margin. Comparison of the lithoclast distribution be- tween sections yields no significant variability. This indicates a rather uniform lateral erosion along the DCP– SB transition zone. The same is also valid for the vertical distribution of litho- clasts in most of the sections. This is expected because most of the logged successions probably 208 belong to the same, single breccia megabed. In the Ponikva-Podbrdo section, which consists of several amalgamated beds, a vertical decrease in Jurassic lithoclasts is visible. This may indi- cate the progressive downcutting erosion of the gravity-flow events, but it could also be attrib- uted to the size of lithoclasts. We noticed that boulder-sized lithoclasts, which characterize the thickest bed of the Podbrdo section (and also oth- er Ponikve Klippe sections) are predominantly Upper Triassic. This could result in the described distribution. Note that in the upper parts of the Podbrdo and Idrija pri Bači sections, which lack the bolder-sized clasts, Jurassic lithoclasts reap- pear in greater number. Backstepping of the Dinaric Carbonate Platform margin The tectonic subsidence (either forced by ex- tension, transtension, or flexural bending) was not limited solely to the slope between the DCP and the SB, but also influenced the wider transi- tion zone. As discussed in the previous chapter, Middle Jurassic lithoclasts from the breccia point to segmentation of the slope/platform margin and the establishment of a step-like paleotopography. Furthermore, the subsidence of the DCP margin is directly evident from its northern-most outcrops. In western Slovenia, these outcrops are charac- terized by Upper Triassic and Lower Jurassic (pre-Toarcian) inner platform (lagoon/intertidal) carbonates. In the Idrijca Valley, Upper Creta- ceous deep-marine (allodapic) limestones of the Volče Limestone Formation directly overlie them (Buser, 1986). This leaves the time of the subsid- ence wide open. Similar conditions are known from the Soča Valley (Ogorelec et al., 1976; Buser, 1986), but the most recent geological study of the Dobler Hydropower area showed that the Lower Jurassic platform limestones are directly overlain by uppermost Jurassic or lowermost Cretaceous deeper marine sediments, i.e. limestone breccia with a calpionellid-rich micritic matrix (Kovač, 2016). This narrows the drowning of this area to the Middle to Late Jurassic period. Similar conditions are described from eastern Slovenia, where Upper Triassic and often Lower Jurassic inner platform carbonates are overlain by latest Jurassic–Berriasian Biancone-type limestone (Babić 1973, 1979; Aničić & Dozet, 2000; Aničičć et al, 2004; Buser, 2010; Poljak, 2017; Rehakova & Rožič, 2019). At Mt. Gorjanci the Lower Juras- sic, so-called Krka Limestone is overlain by the siliceous pelagites that are dated to Bajocian–Ti- thonian (Rižnar, 2006; Skobe et al., 2013; Poljak, 2017). This data from eastern Slovenia indicates that the first prominent subsidence of the DCP margin occurred between the late Early Juras- sic and the latest Late Jurassic. Considering the succession of Mt. Gorjanci, we can narrow this interval to the late Early Jurassic–middle Middle Jurassic. A connection to the DCP margin col- lapse discussed herein appears highly probable. Indications of the (Middle) Jurassic platform margin retreat also appear in the form of the changed position of the Upper Triassic and Upper Jurassic marginal reefs. In this paper (and Rožič et al., 2019), we present evidence for the existence of Upper Triassic reefs on the DCP margin that were located north of the existing platform out- crops. Today, they are covered by South-Alpine nappes (SB successions), or alternatively, could have been largely destroyed by redepositional events described herein. In contrast, Upper Ju- rassic reefs are well known and were paleonto- logically studied in detail (Turnšek, 1997). They are generally located south and southwest of the successions described in the previous paragraph (Fig. 1). These reefal limestones are traced from the Trnovski gozd area, through central Slovenia to Bela Krajina and further SE throughout the External Dinarides (Turnšek et al., 1981; Buser, 1978; 1996; Turnšek, 1997; Vlahović et al., 2005). In western Slovenia, Upper Jurassic reefs are underlain firstly by Middle Jurassic thin-bed- ded limestone with cherts, followed by Middle Jurassic ooidal limestones which gradually pass into thin layers of Toarcian crinoidal limestone. These formations are characteristic of the DCP margin or open shelf. Downwards, these litho- stratigraphic units pass into the abovementioned pre-Toarcian carbonates of the inner platform (lagoon/intertidal environments). From the de- scribed succession, we cannot precisely deter- mine the time of the backstepping, but it must have occurred after the Pliensbachian. While the Toarcian deepening can still be attributed to the major eustatic sea-level rise, the following successions clearly indicate a general shift from inner platform to long-lasting open-marine envi- ronments. In eastern Slovenia (Trebnje area), the Late Jurassic reefs and (fore-reef) breccia overlie the deep-marine hemipelagic and resedimented limestones with cherts, which are probably also Late Jurassic in age. Further downward, beneath a prominent stratigraphic gap, Lower Jurassic limestones equivalent to those from Western Slo- venia, i.e. Toarcian crinoidal/ooidal limestones and pre-Toarcian lagoon/intertidal limestones B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 209A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope are found (Otoničar, 2015). Also from this succes- sion, an approximately Middle Jurassic platform retreat seems entirely plausible. Taking into consideration all of the data pre- sented herein, we propose that the collapse of the platform margin and formation of the Ponikve breccia Member is not the main factor behind the backstepping of the DCP margin. More likely, it represents an extraordinary and extensive sedi- mentary response to the tectonic processes that caused a significant topographic reorganization of the platform-margin–slope–basin transition. Conclusions Hemipelagic sediments and subordinate cal- citurbidites characterize the Jurassic successions of the Slovenian Basin’s southern margin. The main and most striking exception are thick lime- stone breccia beds, which form successions up to 80 meters thick originating from large-scale debris-flows. These are largely dated to the Bajo- cian and early Bathonian, but some also occurred later in the Middle Jurassic. We define this lime- stone breccia as a Ponikve Breccia Member of the Tolmin Formation. Detailed analyses of lithoclasts allowed for a reconstruction of the Dinaric Carbonate Plat- form’s northern margin, which is no longer pre- served nor exposed on the surface due to over- thrusting. In the Upper Triassic, a reef complex typical of other Dachstein-type platforms char- acterized the Dinaric Carbonate Platform mar- gin. In the Lower Jurassic, following the Triassic/ Jurassic Boundary calcification crisis, the Dinar- ic Carbonate Platform margin was dominated by ooidal sand shoals. The Dinaric Carbonate Platform inherited a flat-topped architecture in the early Lower Jurassic and possibly longer. To- wards the end of the Lower Jurassic the platform margin may have partially subsided. Following the Toarcian deepening, shal- low-marine conditions on the Dinaric Carbonate Platform margin were re-established with ooidal shoals. Towards the basin, a slope dissected by fault-escarpments likely existed. In the Bajocian, regional tectonic perturba- tions started to trigger major collapses of the Dinaric Carbonate Platform margin, in turn giv- ing rise to the formation of the Ponikve Breccia. These collapse events changed the architecture of the platform margin and may have brought about the retreat of the Dinaric Carbonate Plat- form margin. These tectonic- and sedimentary- events may also have been at least partially re- sponsible for the present-day non-existing sur- face exposure of the Dinaric Carbonate Platform margin carbonates of the Late Triassic and the Early Jurassic age. Acknowledgments This research was financially supported by the Slovenian Research Agency (research core funding No. P1-0195[B] and No. P1-0011). We acknowledge and thank the reviewers for their thorough review of the manuscript. We thank Primož Miklavc and Ema Hrovatin for the preparation of thin sections. And we would like to thank Jeff Bickert for his copy edit of the text. References Aničić, B. & Dozet, S. 2000: Younger Paleozoic and Mesozoic rocks in the northern Krško de- pression borderland, Slovenia (in Slovenian, with extended English abstract). Geologija, 43/1: 13–35. https://doi.org/10.5474/ geologija.2000.001 Aničić, B., Ogorelec, B. & Dozet, S. 2004: Geološka karta Kozjanskega 1: 25.000 = Geological map of the Kozjansko (Slovenia) 1: 25.000. Geološki zavod Slovenije, Ljubljana. Babić, L. 1973: Upper-Tithonian-to-Valanginian basinal sediments west of Bregana (in Croatian, with extended English abstract). Geološki vjestnik, 26: 11–27. Babić, L. 1979: Limestone with calpionellids on Mt. Rudnica (eastern Slovenia) (in Croatian, with extended English abstract). Geološki vjestnik, 31: 13–20. Bernecker, M. 2005: Late Triassic reefs from the Northwest and South Tethys: distribution, setting, and biotic composition. Facies, 51/1: 442–453. Berra, F., Galli, M., Reghellin, F., Torricelli, S. & Fantoni, R. 2009: Stratigraphic evoluti- on of the Triassic-Jurassic succession in the western Southern Alps (Italy): The record of the two-stage rifting on the distal passive margin of Adria. Basin Research, 21: 335–353. Bertotti, G., Picotti, V., Bernoulli, D. & Castellarin, A. 1993: From rifting to drif- ting: Tectonic evolution of the Southalpine upper crust from the Triassic to the early Cretaceous. Sedimentary Geology, 86/1-2: 53–76. Bill, M., O’Dogherty, L., Guex, J., Baumgartner, P. O. & Masson, H. 2001: Radiolarite ages in Alpine-Mediterranean ophiolites: Constraints on the oceanic spreading and the Tethys 210 Atlantic connection. Geological Society of America Bulletin, 113: 129–143. Blomeier, D. P. G. & Reijmer, J. J. G. 2002: Facies Architecture of an Early Jurassic Carbonate Platform Slope (Jbel Bou Dahar, High Atlas, Morocco). Journal of Sedimentary Research, 72/4: 462–475. https://doi. org/10.1306/111501720462 Böhm, F., Ebli, O., Krystyn, L., Lobitzer, H., Rakús, M. & Siblik, M. 1999: Fauna, strati- graphy and depositional environment of the Hettangian-Sinemurian (Early Jurassic) of Adnet (Salzburg, Austria). Abhandlungen der Geologiscgen Bundesanstalt, 56: 143–271. Borojević Šoštarić, S., Palinkaš, L., Neubauer, F., Cvetković, V., Bernroider, M. & Genser, J. 2014: The origin and age of the metamorphic sole from the Rogozna Mts., Western Vardar Belt: New evidence for the one-ocean model for the Balkan ophiolites. Lithos, 192-195: 39– 55. https://doi.org/10.1016/j.lithos.2014.01.011. Bortolotti, V., Chiari, M., Marroni, M., Pandolfi, L., Principi, G. & Saccani, E. 2013: Geodynamic evolution of ophiolites from Albania and Greece (Dinaric-Hellenic belt): One, two, or more oceanic basins? International Journal of Earth Sciences, 102: 783–811. Bragin, N. & Djeric, N. 2020: Age of the Jurassic hemipelagic sediments from the Ljubiš area (Zlatibor Mt., SW Serbia). Geologia Croatica, 73/3: 143–151. https://doi.org/10.4154/ gc.2020.11 Bucković, D. 2006: Jurassic section of Gorski Kotar (Western Karst Dinarides, Croatia) fa- cies characteristics, depositional setting and paleogeographic implications. Acta Geologica Hungarica, 49/4: 331–354. Buser, S. 1965: Stratigrafski razvoj jurskih skla- dov na južnem Primorskem, Notranjskem in zahodni Dolenjski: disertacija. Univerza v Ljubljani, Ljubljana: 101 f. Buser, S. 1978: Razvoj jurskih plasti Trnovskega gozda, Hrušice in Logaške planote. Rudarsko – metalurški zbornik, 4: 385–406. Buser, S. 1986: Basic Geological Map SFRJ 1:100.000. Explanatory Booklet. Zvezni geo- loški zavod Jugoslavije, Beograd. 103 p. Buser, S. 1989: Development of the Dinaric and Julian carbonate platforms and the inter- mediate Slovenian basin (NW Yugoslavia). In: Carulli, G. B., Cucchi, F. & Radrizzani, C. P. (eds.): Evolution of the karstic carbona- te platform: Relation with other periadriatic carbonate platforms. Memorie della Società Geologica Italiana, 40: 313–320. Buser, S. 1996: Geology of western Slovenia and its paleogeographic evolution. In: Drobne, K., Goričan, Š. & Kotnik, B. (eds.): The role of Impact Processes in the Geological and Biological Evolution of Planet Earth. International workshop, ZRC SAZU: 111–123. Buser, S. 2010: Geological map of Slovenia 1: 250.000. Geološki zavod Slovenije, Ljubljana. Buser, S. & Debeljak, I. 1996: Lower Jurassic beds with bivalves in south Slovenia. Geologija, 37/38: 23–62. https://doi. org/10.5474/geologija.1995.001 Buser, S. & Dozet, S. 2009: Jura = Jurassic. In: Pleničar, M., Ogorelec, B. & Novak, M. (eds.): Geologija Slovenije = The geology of Slovenia. Geološki zavod Slovenije, Ljubljana: 215–254. Buser, S., Ramovš, A. & Turnšek, D. 1982: Triassic Reefs in Slovenia. Facies, 6: 15–24. Caron, M. & Homewood, P. 1983: Evolution of early planktic foraminifers. Marine Micropaleontology, 7: 453–462. Chiari, M., Cobianchi, M. & Picotti, V. 2007: Integrated stratigraphy (radiolarians and cal- careous nannofossils) of the Middle to Upper Jurassic Alpine radiolarites (Lombardian ba- sin, Italy): Constraints to their genetic interpre- tation. Palaeogeography, Palaeoclimatology, Palaeoecology, 249/3-4: 233–270. https://doi. org/10.1016/j.palaeo.2007.02.001 Chiari, M., Marcucci, M. & Principi, G. 2000: The age of the radiolarian cherts associated with the ophiolites in the Apennines (Italy) and Corsica (France): A revision. Ofioliti, 25: 141–146. Cirilli, S., Iannace, A., Jadoul, F. & Zamparelli, V. 1999: Microbial-serpulid build-ups in the Norian-Rhaetian of the western Mediterranean area: ecological response of shelf margin communities to stressed envi- ronments. Terra Nova-Oxford, 11/5: 195–202. Clari, P. & Masetti, D. 2002: The Trento Ridge and the Belluno Basin. In: Santantonio, M. (ed.): General Field Trip Guidebook, VI International Symposium on the Jurassic System, 12 22 September 2002: 271–315. Cohen, K. M., Finney, S. C., Gibbard, P.L. & Fan, J. -X. 2013: updated The ICS International Chronostratigraphic Chart. Episodes, 36/3: 199–204. Cousin, M. 1981: Les repports Alpes – Dinarides. Les confins de I’talie et de la Yougoslavie. Annales de la Société géologique du Nord, 5/1: 1-521. Čadjenović, D., Kilibarda, Z. & Radulović, N. 2008: Late Triassic to Late Jurassic evolution B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 211A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope of the Adriatic carbonate platform and Budva Basin, southern Montenegro. Sedimentary Geology, 204/1-2: 1–17. Črne, A. E. & Goričan, Š. 2008: The Dinaric Carbonate Platform margin in the Early Jurassic: A comparison between successions in Slovenia and Montenegro. Bollettino della Società Geologica Italiana, 127: 389–405. Darling, K. F., Wade, C. M., Kroon, D. & Brown, A. J. L. 1997: Planktic foraminiferal molecular evolution and their polyphyletic origins from benthic taxa. Marine Micropaleontology, 30: 251–266. De Graciansky, P. C., Roberts, D. G. & Tricart, P. 2011: The Western Alps, from rift to passive margin to orogenic belt: An integrated geos- cience overview. Elsevier, Amsterdam: 432 p. Della Porta, G., Merino-Tomé, O., Kenter, J. A. M. & Verwer, K. 2014: Lower Jurassic Microbial and Skeletal Carbonate Factories and Platform Geometry (Djebel Bou Dahar, High Atlas, Morocco). In: Verwer, K., Playton, T. E. & Harris, P. M. (eds.): Deposits, Architecture, and Controls of Carbonate Margin, Slope and Basinal Settings. SEPM Special Publication, 105: 237–263. Demšar, M. 2016: Geological map of the Selca val- ley 1:25.000. Explanatory Booklet. Geološki Zavod Slovenije, Ljubljana: 71 p. Dozet, S., 2009: Lower Jurassic carbonate su- ccession between Predole and Mlačevo, Central Slovenia = Spodnjejursko karbonat- no zaporedje med Predolami in Mlačevim, osrednja Slovenija. RMZ–Materials and geo- environment, 56/2: 164–193. Dozet, S. & Ogorelec, B. 2012: Younger paleozo- ic, mesozoic and tertiary oolitic and oncolitic beds in Slovenia – An Overview. Geologija, 55/2: 181–208. https://doi.org/10.5474/ geologija.2012.012 Dozet, S. & Strohmenger, C. 2000: Podbukovje Formation, central Slovenia. Geologija, 43/2: 197–212. https://doi.org/10.5474/ geologija.2000.014 Dragičević, I. & Velić, I. 2002: The Northeastern Margin of the Adriatic Carbonate Platform. Geologia Croatica, 55/2: 185–232. Dunham, R. J. 1962: Classifications of carbonate rocks according to depositional texture. In: Ham, E. W. (ed.): Classification of carbonate rocks: A symposium. American Association of Petroleum Geologists Memoir, 1: 108–122. Embry, A. F. & Klovan, J. E. 1971: A late Devonian reef tract on northeastern Banks Island, N.W.T. Bulletin of Canadian Petroleum Geology, 19: 730–781. Fisher, A.G. 1964: The Lofer cyclothems of the Alpine Triassic. Kansas geological Survey Bulletin, 169: 107–149. Flügel, E. 2004: Microfacies of carbonate rocks: Analysis, interpretation and application. Springer, Berlin: 976 p. Franceschi, M., Massironi, M., Franceschi, P. & Picotti, V. 2013: Study of the Early Jurassic Calcari Grigi carbonate platform (Southern Alps, Italy) integrating 3D-modeling and ge- ostatistics. Rend. Online Soc. Geol. It., 29: 59–62. Gale, L. 2010: Microfacies analysis of the Upper Triassic (Norian) »Bača Dolomite«: Early evolution of the western Slovenian Basin (eastern Southern Alps, western Slovenia). Geologica Carpathica, 61: 293–308. https:// doi.org/10.2478/v10096-010-0017-0 Gale, L. 2012: Rhaetian foraminiferal assem- blage from the dachstein limestone of Mt. Begunjščica (Košuta unit, eastern Southern Alps). Geologija, 55/1: 17–44. https://doi. org/10.5474/geologija.2012.002 Gale, L., Kastelic, A. & Rožič, B. 2013: Taphonomic features of Late Triassic foraminifera from Mount Begunjščica, Karavanke Mountains, Slovenia. Palaios, 28: 771–792. https://doi. org/10.2110/palo.2014.102 Gale, L. & Kelemen, M. 2017: Early Jurassic fora- miniferal assemblages in platform carbona- tes of Mt. Krim, central Slovenia. Geologija, 60/1: 99–115. https://doi.org/10.5474/ geologija.2017.008 Gale, L., Kolar-Jurkovšek, T., Šmuc, A. & Rožič, B. 2012: Integrated Rhaetian foraminife- ral and conodont biostratigraphy from the Slovenian Basin, Eastern Southern Alps. Swiss Journal of Geosciences, 105/3: 435–462. Gale, L., Rožič, B., Mencin, E. & Kolar-Jurkovšek, T. 2014: First evidence for Late Norian progra- dation of Julian Platform towards Slovenian Basin, Eastern Southern Alps. Rivista Italiana di Paleontologia e Stratigrafia, 120: 191–214. Gale, L., Skaberne, D., Peybernes, C., Martini, R., Čar, J. & Rožič, B. 2016: Carnian reefal bloc- ks in the Slovenian Basin, eastern Southern Alps. Facies 62/23. https://doi.org/10.1007/ s10347-016-0474-8 Gallhofer, D., von Quadt, A., Schmid, S. M., Guillong, M., Peytheva, I. & Seghedi, I. 2017: Magmatic and tectonic history of Jurassic op- hiolites and associated granitoids from the 212 South Apuseni Mountains (Romania). Swiss Journal of Geosciences, 110: 699–719. https:// doi.org/10.1007/s00015-016-0231-6 Gawlick, H.J. & Missoni, S. 2019: Middle-Late Jurassic sedimentary mélange formation re- lated to ophiolite obduction in the Alpine- Carpathian-Dinaridic Mountain Range. Gondwana Research, 74: 144–172. Gawlick, H.-J., Djerić, N., Missoni, S., Bragin, N. Y., Lein, R., Sudar, M. & Jovanović, D. 2017a: Age and microfacies of oceanic Upper Triassic radiolarite components from the Middle Jurassic ophiolitic mélange in the Zlatibor Mountains (Inner Dinarides, Serbia) and their provenance. Geologica Carpathica, 68/4: 350–365. Gawlick, H.-J., Missoni, S., Schlagintweit, F., Suzuki, H., Frisch, W., Krystyn, L., Blau, J. & Lein, R. 2009: Jurassic Tectonostratigraphy of the Austroalpine domain. Journal of Alpine Geology, 50: 1–152. Gawlick, H.-J., Missoni, S., Sudar, M., Goričan, Š., Lein, R., Stanzel, A. I. & Jovanović, D. 2017b: Open-marine Hallstatt Limestones reworked in the Jurassic Zlatar Mélange (SW Serbia): A contribution to understanding the orogenic evolution of the Inner Dinarides. Facies, 63/29. https://doi.org/10.1007/s10347-017-0510-3 Gawlick, H.-J., Missoni, S., Suzuki, H., Sudar, M., Lein, R. & Jovanović, D. 2016: Triassic radiolarite and carbonate components from the Jurassic ophiolitic mélange (Dinaridic Ophiolite Belt). Swiss Journal of Geosciences, 109: 473–494. Gawlick, H. J., Sudar, M. N., Missoni, S., Suzuki, H., Lein, R., & Jovanović, D. 2017c: Triassic- Jurassic geodynamic history of the Dinaridic Ophiolite Belt (Inner Dinarided, SW Serbia). Journal of Alpine geology, 55: 1–167. Gerčar, D. 2017: Sedimentologija in stratigra- fija jurske apnenčeve blokovne breče na Ponikvanski tektonski krpi = Sedimentology and stratigraphy of Jurassic limestone bloc- ky breccia from Ponikve tectonic klippe. Magistrsko delo, Naravoslovnotehniška Fakulteta, Ljubljana: 60 p. Goričan, Š., Pavšič, J. & Rožič, B. 2012: Bajocian to Tithonian age of radiolarian cherts in the Tolmin Basin (NW Slovenia). Bulletin de la Société géologique de France, 183: 369–382. Haas, J. 2004: Characteristics of peritidal faci- es and evidences for subaerial exposures in Dachstein-type cyclic platform carbonates in the Transdanubian Range, Hungary. Facies, 50: 263–286. Haas, J., Götz, A.E. & Pálfy, J. 2010: Late Triassic to Early Jurassic palaeogeography and eusta- tic history in the NW Tethyan realm: New in- sights from sedimentary and organic facies of the Csővár Basin (Hungary). Palaeogeography, Palaeoclimatology, Palaeoecology, 291/3-4: 456–468. Haas, J., Gawlick, H.J., Kovacs, S., Karamata, S., Sudar, M., Gradinaru, E., Mello, J., Pollak, M., Halamic, J., Tomljenovic, B. & Ogorelec, B. 2006: Jurassic environments in the Circum-Pannonian region. In: Proceedings XVIIIth Congress of the Carpathian-Balkan Geological Association. Slovak Academy of Sciences, Bratislava: 201–204. Iannace, A. & Zamparelli, V. 2002: Upper Triassic platform margin biofacies and the paleogeography of Southern Apennines. Palaeogeography, Palaeoclimatology, Palaeoecology, 179/1-2: 1–18. Iveković, A. 2008: Stratigrafsko - sedimen- tološki razvoj jurskih in krednih kamnin v dolini reke Mirne. Diplomsko delo, Naravo- slovnotehniška Fakulteta, Ljubljana: 89 p. Kiessling, W., Aberhan, M., Brenneis, B. & Wagner, P. J. 2007: Extinction trajectories of benthic organisms across the Triassic–Jurassic bou- ndary. Palaeogeography, Palaeoclimatology, Palaeoecology, 244: 201–222. Kovács, S., Sudar, M., Gradinaru, E., Karamata, S., Gawlick, H. J., Haas, J., Péró, C., Gaetani, M., Mello, J., Polák, M., Aljinović, D., Ogorelec, B., Kolar-Jurkovšek, T., Jurkovsek, B. & Buser, S. 2011: Triassic evolution of the tectonostratigraphic units in the Circum- Pannonian region. Jahrbuch der Geologischen Bundesanstalt, 151: 199–280. Kovač, A. 2016: Biostratigrafija in sedimentologi- ja srednjejurskih in spodnjekrednih plasti v dolini Soče pri HE Doblar = Biostratigraphy and sedimentology of Middle Jurassic to Lower Cretaceous beds in Soča Valley by the HE Doblar. Diplomsko delo, Nara- voslovnotehniška fakulteta, Ljubljana: 61 p. Kuss, J. 1983: Faziesentwicklung in proxima- len Intraplattform-Becken: Sedimentation, Palökologie und Geochemie der Kössener Schichten (Ober-Trias, Nördliche Kalkalpen). Facies, 9/1: 61–171. Le Breton, E., Brune, S., Ustaszewski, K., Zahirović, S., Seton, M. & Müller, R. D. 2021: Kinematics and extent of the Piemont– Liguria Basin – implications for subduction processes in the Alps. Solid Earth, 12/4: 885– 913. https://doi.org/10.5194/se-12-885-2021 B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 213A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Leinfelder, R., Schmid, D. U., Nose, M. & Werner, W. 2002: Jurassic Reef Patterns - The Expression of a Changing Globe Phanerozoic Reef Patterns. SEPM Special Publication, 72: 465–520. https://doi.org/10.2110/ pec.02.72.0465 Manatschal, G. & Müntener, O. 2009: A type sequence across an an ancient magma-po- or ocean-continent transition: The example of the western Alpine Tethys ophiolites. Tectonophysics, 473/1–2: 4–19. https://doi. org/10.1016/l.tecto.2008.07.021. Mandl, G. W. 2000: The Alpine sector of the Tethyan shelf – Examples of Triassic to Jurassic sedimentation and deformation from the Northern Calcareous Alps. Mitteilungen der Österreichischen Mineralogischen Gesellschaft, 92: 61–77. Martindale, R.C., Krystyn, L., Corsetti, F.A., & Bottjer, D.J. 2013: From fore reef to lagoon: evolution of the Upper Triassic Dachstein carbonate platform on the Tennengebirge (Salzburg, Austria). Palaios, 28: 755–770. Martinuš, M., Bucković, D. & Kukoč, D. 2012: Discontinuity surfaces recorded in shallow- -marine platform carbonates: an example from the Early Jurassic of the Velebit Mt.(Croatia). Facies, 58/4: 649–669. Martire, L. 1996: Stratigraphy, facies and syn- sedimentary tectonics in the Jurassic Rosso Ammonitico Veronese (Altopiano di Asiago, NE Italy). Facies, 35: 209–236. Martire, L., Clari, P., Lozar, F. & Pavia, G. 2006: The Rosso Ammonitico Veronese (Middle– Upper Jurassic of the Trento Plateau): A pro- posal of lithostratigraphic ordering and for- malization. Rivista Italiana Paleontologia e Stratigrafia, 112: 227–250. Masetti, D., Fantoni, R., Romano, R., Sartorio, D. & Trevisani, E. 2012: Tectonostratigraphic evolution of the Jurassic extensional basins of the eastern southern Alps and Adriatic foreland based on an integrated study of surface and subsurface data. American Association of Petroleum Geologists Bulletin, 96: 2065–2089. Masini, E., Manatschal, G. & Mohn, G. 2013: The Alpine Tethys rifted margins: Reconciling old and new ideas to understand the stratigrap- hic architecture of magma-poor rifted mar- gins. Sedimentology, 60: 174–196. Merino-Tomé, O., Della Porta, G., Kenter, J. A. M., Verwer, K., Harris, P. M., Adams, E., Playton, T. & Corrochano, D. 2012: Sequence development in an isolated carbonate platform (Lower Jurassic, Djebel Bou Dahar, High Atlas, Morocco): influence of tecto- nics, eustacy and carbonate production. Sedimentology, 59/1: 118–155. https://doi. org/10.1111/j.1365-3091.2011.01232.x Mikes, T., Christ, D., Petri, R., Dunkl, I., Frei, D., Baldi-Beke, M., Reitner, J., Wemmer, K., Hrvatović, H. & von Eynatten, H. 2008: Provenance of Bosnian Flysch. Swiss Journal of Geosciences, 101/31: 31–54. https://doi. org/10.1007/s00015-008-1291-z Miler, M. & Pavšič, J. 2008: Triassic and Jurassic beds in Krim Mountain area Slovenija. Geologija, 51/1: 87–99. https://doi.org/10.5474/ geologija.2008.010 Ogorelec, B. 2011: Microfacies of Mesozoic carbo- nate rocks of Slovenia. Geologija, 54: 1–136. Ogorelec, B. & Rothe, P. 1993: Mikrofazies, Diagenese und Geochemie des Dachsteinkalkes und Hauptdolomits in Süd-West-Slowenien. Geologija, 35: 81–182. https://doi.org/10.5474/geologija.1992.005 Ogorelec, B. & Buser, S. 1996. Dachstein Lime- stone from Krn in Julian Alps (Slovenia). Geologija, 39: 133–157. https://doi.org/10.5474/ geologija.1996.006 Ogorelec, B. & Dozet, S. 1997: Upper Triassic, Jurassic and Lower Cretaceous beds in eastern Sava Folds - Section Laze at Boštanj (Slovenia). RMZ-Materials and geoenvi- ronment, 44/3-4: 223–235. Ogorelec, B., Šribar, L. & Buser, S. 1976: O lito- logiji in biostratigrafiji Volčanskega apnenca. Geologija Revija, 19: 125–151. Oprčkal, P., Gale, L., Kolar-Jurkovšek, T. & Rožič, B. 2012: Outcrop-scale evidence for the norian-rhaetian extensional tectonics in the Slovenian basin (Southern Alps). Geologija, 55: 45–56. Otoničar, B. 2015: Evolucija severovzhodnega ob- robja Jadranske karbonatne platforme med zgornjim triasom in zgornjo juro (Dolenjska, JV Slovenija). In: Rožič, B. (ed.): Razprave, poročila = Treatises, reports, 22. posveto- vanje slovenskih geologov = 22nd Meeting of Slovenian Geologists. Univerza v Ljubljani, Naravoslovnotehniška fakulteta, Oddelek za geologijo, 23: 147–150. Piller, W.E. 1981: The Steinplatte reef complex, part of an Upper Triassic carbonate plat- form near Salzburg, Austria. SEPM Special Publication, 30: 261–290. Placer, L. 1999: Contribution to the macrotecto- nic subdivision of the border region between 214 Southern Alps and External Dinarides. Geologija, 41: 223–255. Placer, L. 2008: Principles of the tectonic subdi- vision of Slovenia. Geologija, 51/2: 205–217. https://doi.org/10.5474/geologija.2008.021 Poljak, M. 2017: Geological Map of the Eastern Part of the Krško Basin 1:25,000. Explanatory Booklet. Geološki Zavod Slovenije, Ljubljana: 108 p. Praprotnik Kastelic, J., Kastelic, A., Gale, L., Šmuc, A. & Rožič, B. 2013: Jurske plasti z man- ganovimi obogatitvami na Begunjščici. In: Rožič, B. (ed.): Razprave, poročila = Treatises, reports. 21. posvetovanje slovenskih geologov, Ljubljana, 2013 = 21st Meeting of Slovenian Geologists. Naravoslovnotehniška fakulteta, Ljubljana: 127–130. Ramovš, A. 1994: O starosti škofjeloških ploščas- tih apnencev z roženci. Loški razgledi, 41/1. Reháková, D. & Rožič, B. 2019: Calpionellid bio- stratigraphy and sedimentation of the Biancone limestone from the Rudnica Anticline (Sava Folds, eastern Slovenia). Geologija, 62/1: 89- 101. https://doi.org/10.5474/geologija.2019.004 Ribes, C., Manatschal, G., Ghienne, J. F., Karner, G. D., Johnson, C. A., Figueredo, P. H., Incerpi, N. & Epin, M. E. 2019: The syn-rift stratigraphic record across a fossil hyper- -extended rifted margin: the example of the northwestern Adriatic margin exposed in the Central Alps, International Journal of Earth Sciences, 108: 2071–2095. https://doi. org/10.1007/s00531-019-01750-6 Ribes, C., Petri, B., Ghienne, J. F., Manatschal, G., Galster, F., Karner, G. D., Figueredo, P. H., Johnson, C. A. & Karpoff, A. M. 2020: Tectono-sedimentary evolution of a fossil ocean-continent transition: Tasna nappe, central Alps (SE Switzerland), Geological Society of America Bulletin, 132: 1427–1446. https://doi.org/10.1130/B35310.1 Rižnar, I. 2006: History of research of the Krško and Veliki trn beds (revision). Dela SAZU, IV. Razreda, 47: 79–99. Rožič, B. 2005: Albian–Cenomanian resedimen- ted limestone in the Lower Flyschoid forma- tion of the Mt. Mrzli Vrh Area (Tolmin regi- on, NW Slovenia). Geologija, 48/2: 193-210. https://doi.org/10.5474/geologija.2005.017 Rožič, B. 2006: Sedimentology, stratigraphy and geochemistry of Jurassic rocks in the western part of the Slovenian Basin. Ph.D. thesis, University of Ljubljana, Ljubljana: 148 p. Rožič, B. 2009: Perbla and Tolmin formations: Revised Toarcian to Tithonian stratigraphy of the Tolmin Basin (NW Slovenia) and regio- nal correlations. Bulletin de la Société géolo- gique de France, 180: 411–430. Rožič, B. 2016: Paleogeographic units. In: Novak, M. & Rman, N. (eds.): Geological atlas of Slovenia. Geološki zavod Slovenije, Ljubljana: 14–15. Rožič, B., Gale, L. & Kolar-Jurkovšek, T. 2013: Extent of the Upper Norian-Rhaetian Slatnik formation in the Tolmin nappe, Eastern Southern Alps. Geologija, 56/2: 175-186. https://doi.org/10.5474/geologija.2013.011 Rožič, B., Gale, L., Oprčkal, P., Švara, A., Udovč, J., Debevec, G., Popit, T., Vrabec, M. & Šmuc, A. 2015: Stratigrafija in strukturni pomen kamnin Slovenskega bazena pri Škofji Loki. Geološki zbornik, 23: 171–175. Rožič, B., Gerčar, D., Oprčkal, P., Švara, A., Turnšek, D., Kolar-Jurkovšek, T., Udovč, J., Kunst, L., Fabjan, T., Popit, T. & Gale, L., 2019: Middle Jurassic limestone megabreccia from the southern margin of the Slovenian Basin. Swiss Journal of Geosciences, 112/1: 163–180. https://doi.org/10.1007/s00015-018-0320-9 Rožič, B., Goričan, Š., Švara, A. & Šmuc, A. 2014a: The Middle Jurassic to Lower Cretaceous succession of the Ponikve klippe: The Southernmost outcrops of the Slovenian Basin in Western Slovenia. Rivista Italiana di Paleontologia e Stratigrafia, 120: 83–102. Rožič, B., Kolar-Jurkovšek, T. & Šmuc, A. 2009: Late Triassic sedimentary evolution of Slovenian Basin (eastern Southern Alps): Description and correlation of the Slatnik Formation. Facies, 55: 137–155. https://doi. org/10.1007/s10347-008-0164-2 Rožič, B., Kolar-Jurkovšek, T., Žvab Rožič, P. & Gale, L. 2017: Sedimentary record of subsi- dence pulse at the Triassic/Jurassic bounda- ry interval in the Slovenian Basin (eastern Southern Alps). Geologica Carpathica, 68: 543–561. https://doi.org/10.1515/ geoca-2017-0036 Rožič, B. & Popit, T. 2006: Resedimented limesto- nes in Middle and Upper Jurassic succession of the Slovenian Basin. Geologija, 49/2: 219– 234. https://doi.org/10.5474/geologija.2006.016 Rožič, B., Udovč, J. Žvab Rožič, P., Gale, L. & Gerčar, D. 2022: How far to the west was the Slovenian basin extending?. In: Program, Abstracts and Field Trip Guide. Budapest: 97. Rožič, B., Venturi, F. & Šmuc, A. 2014b: Ammonites from Mt Kobla (Julian Alps, NW Slovenia) and their significance for precise dating of Pliensbachian tectono-sedimentary B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR 215A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope event. RMZ - Materials and geoenvironment, 61/2-3: 191–201. Sabatino, N., Vlahović, I., Jenkyns, H. C., Scopelliti, G., Neri, R., Prtoljan, B. & Velić, I. 2013: Carbon-isotope record and palaeoenvi- ronmental changes during the early Toarcian oceanic anoxic event in shallow-marinecar- bonates of the Adriatic Carbonate Platform in Croatia. Geological Magazine, 150/6: 1085–1102. Samankassou, E. & Enos, P. 2019: Lateral faci- es variations in the Triassic Dachstein plat- form: A challenge for cyclostratigraphy. The Depositional Record, 5/3: 469–485. Satterley, A.K. 1996: The interpretation of cyclic successions of the Middle and Upper Triassic of the Northern and Southern Alps. Earth- Science Reviews, 40/3-4: 181–207. Schäfer, P. & Senowbari-Daryan, B. 1981: Facies Development and Paleoecologic Zonation of Four Upper Triassic Patch Reefs Northern Calcareous Alps Near Salzburg Austria. SEPM Special Publication, 30: 241–259. Scherman, B., Rožič, B., Görög, A., Kövér, S. & Fodor, L. 2022: Platform to basin transiti- ons: mapping observations at the Krvavica Mountain, and Čemšeniška Planina, in the Sava Folds Region. In: Rožič, B. & Žvab Rožič, P. (eds): 15th Emile Argand Conference on Alpine Geological Studies: abstract book & fieldtrip guide. Faculty of Natural Sciences and Engineering, Ljubljana: 61. Schmid, S. M., Bernoulli, D., Fügenschuh, B., Maßenco, L., Schefer, S., Schuster, R., Tischler, M. & Ustaszewski, K. 2008: The Alpine-Carpathian-Dinarideorogenic system: Correlation and evolution of tectonic units. Swiss Journal of Geosciences, 101: 139–183. Schmid, S.M., Fügenschuh, B., Kounov, A., Maţenco, L., Nievergelt, P., Oberhänsli, R., Pleuger, J., Schefer, S., Schuster, R., Tomljenović, B., Ustaszewski, K. & van Hinsbergen, D. J. J., 2020. Tectonic units of the Alpine collision zone between Eastern Alps and western Turkey. Gondwana Research 78: 308–374. https://doi.org/10.1016/j. gr.2019.07.005 Scheibner, C. & Reijmer, J. G. 1999: Facies pa- tterns within a Lower Jurassic upper slope to inner platform transect (Jbel Bou Dahar, Morocco), Facies 41/1: 55–80. https://doi. org/10.1007/BF02537460 Skobe, S., Goričan, Š., Skaberne, D., Verbič, T., Mišič, M. & Zupančič, N. 2013. K-feldspar rich shales from Jurassic bedded cherts in southeastern Slovenia. Swiss J Geosci 106: 491–504. https://doi.org/10.1007/ s00015-013-0147-3 Šmuc, A. 2005: Jurassic and Cretaceous stra- tigraphy and sedimentary evolution of the Julian Alps, NW Slovenia. Založba ZRC, Ljubljana: 98 p. Šmuc, A. 2012: Middle to Upper Jurassic su- ccession at Mt Kobariški Stol (NW Slovenia) = srednje- do zgornjejursko zaporedje na Kobariškem Stolu (SZ Slovenija). RMZ- Materials and geoenvironment, 59: 267–284. Šmuc, A. & Goričan, Š. 2005: Jurassic sedimentary evolution of a carbonate platform into a deep- -water basin, Mt. Mangart (Slovenian-Italian border). Rivista Italiana di Paleontologia e Stratigrafia, 111: 45–70. Šmuc, A. & Rožič, B. 2010: The Jurassic Prehodavci Formation of the Julian Alps: Easternmost outcrops of Rosso Ammonitico in the Southern Alps (NW Slovenia). Swiss Journal of Geosciences, 103: 241–255. Tappan, H. & Loeblich, A. R. 1988: Foraminiferal evolution, diversification, and extinction. Journal of Paleontology, 62: 695–714. Tišljar, J., Vlahović, I., Velić, I. & Sokač, B. 2002: Carbonate platform megafacies of the Jurassic and Cretaceous deposits of the Karst Dinarides. Geologia Croatica, 55: 139–170. Turnšek, D. 1997: Mesozoic corals of Slovenia. Založba ZRC, Ljubljana: 512 p. Turnšek, D., Buser, S. & Ogorelec, B. 1981: An Upper Jurassic reef complex from Slovenia, Yugoslavia, SEPM Special Publication, 3: 361–369. Turnšek, D., Buser, S. & Debeljak, I. 2003: Liassic coral patch reef above the »Lithiotid limesto- ne« on Trnovski gozd plateau, west Slovenia. Razprave = Dissertationes, 44: 285–331. Turnšek, D. & Košir, A. 2000: Early Jurassic co- rals from Krim Mountain, Slovenia. Razprave = Dissertationes, 41: 81–113. Udovč, J. 2019: Sedimentologija in stratigra- fija jurskih plasti na Matajurju = Sedime- ntology and stratigraphy of Jurassic su- ccession from Mt. Matajur. Magistrsko delo, Naravoslovnotehniška Fakulteta, Ljubljana: 63 p. Valand, N., Rožič, B. & Gale, L. 2019: Jursko zapo- redje z apnenčevimi brečami na južnih pobo- čjih Begunjščice. In: Rrožič, B. (ed.): Razprave, poročila = Treatises, reports. 24. posvetovanje slovenskih geologov = 24th Meeting of Sloveni- an Geologists. Naravoslovnotehniška fakul- teta, Ljubljana. Geološki zbornik, 25: 143–145. 216 Velić, I. 2007: Stratigraphy and palaeobiology of Mesozoic benthic foraminifera of the Karst Dinarides (SE Europe). Geologia Croatica, 60: 1–113. Vlahović, I., Tišljar, J., Velić, I. & Matičec, D. 2005: Evolution of the Adriatic Carbonate Platform: Palaeogeography, main events and depositional dynamics. Palaeogeography, Palaeoclimatology, Palaeoecology, 220: 333–360. Vrabec, M. & Fodor, L. 2006: Late Cenozoic tectonics of Slovenia: structural styles at the Northeastern corner of the Adriatic microp- late. In: Pinter, N., Grenerczy, G., Weber, J., Medak, D. & Stein, S. (eds.): The Adria mi- croplate: GPS geodesy, tectonics and hazards. Springer, Dordrecht: 151–168. Wilson, J. L. 1975: Carbonate facies in geologic history. Springer, Berlin: 471 p. Wurm, D. 1982: Mikrofazies, Paläontologie und Palökologie der Dachsteinriffkalke (Nor) des Gosaukammes, Österreich. Facies, 6/1: 203–295. B. ROŽIČ, L. GALE, P. OPRČKAL, A. ŠVARA, T. POPIT, L. KUNST, †D. TURNŠEK, T. KOLAR-JURKOVŠEK, A. ŠMUC, A. IVEKOVIČ, J. UDOVČ & D. GERČAR