GEOLOGIJA 31, 32, 351-394 (1988/89), Ljubljana
UDK 552.5:551.763.781(497.12) = 20
Microfacies analysis of limestones from the Upper
Cretaceous to the Lower Eocene of SW Slovenia
(Yugoslavia)
David Delvalle
Institut für Sedimentforschung, Universität Heidelberg,
Im Neuenheimer Feld 236, D-6900 Heidelberg, BRD
Stanko Buser
Geološki zavod Ljubljana, Dimičeva 14, 61000 Ljubljana
Abstract
A microfacies analysis of limestone samples from NW Yugoslavia (Slovenia)
was carried out. The microscopic observations were complemented with palynolo-
gical and geochemical data including determination of isotopie ratios. The fin-
dings point to a regressive development which took place during the Senonian and
culminated in karst and subsequent bauxitization. In a later stage of subaerial
exposure, calichification occurred overlapping the karst facies. At the beginning
of the Tertiary, a transgression unfolded and the Kozina limestones started to
form. Due to sea level changes and climatic factors, these sediments show supe-
rimposed palustrine and brackish intertidal to subtidal horizons which were
diagenetically altered thus presenting a complicated facies pattern. Overlaying
the Kozina limestones, the Late Paleocene Miliolid limestones occur. These are
brackish intertidal to subtidal sediments that underwent prolonged periods of
subaerial exposure, too. There is a gradual predominance of marine organisms in
the vertical sequence that reaches its maximum in the next unit, the Alveolina-
Nummulites limestones (Early Eocene). The three stratigraphie units dealt with in
this study reflect gradual but important facies changes which are stressed here.
Introduction
Stanko Buser
The present study gives a reconstruction of the fades development that took place
during the time interval from Upper Cretaceous to Early Eocene in SW Slovenia.
The analysis focuses on the interpretation of the depositional environments and
diagenesis of the Tertiary limestones, especially of the limestones that were deposited
at the beginning of the Tertiary age, the Kozina limestones.
Severalinvestigators(Stache, 1889; Hamrla, 1960; Pleničar, 1961; Pavlo-
vec, 1963; Drobne et al, 1988) consider these limestones to have been originated
under most diverse conditions. Among the proposed depositional settings there are
lakes, estuaries and brackish lagoons. The Kozina beds also show marine intercalati-
352 David Delvalle & Stanko Buser
ons rendering the facies spectrum almost complete. This facies complexity is gene-
rally taken to be the result of tectonic instability since the Laramian movements of
the Alpine orogenesis were still active in the area at the beginning of the Tertiary.
Taken as a whole, the entire Tertiary sequence shows a clear transgressive
character which is, of course, unthinkable without tectonics.
Last but not least, the authors refer to the Cretaceous-Tertiary boundary in the
studied area which is marked by an unconformity that can be easily recognized in the
field. Moreover, this boundary shows some interesting features that may help to
interpret the subsequent facies development.
Tectonic structure of the investigated territory
Regarding the broadest geotectonic division of Slovenia, the discussed territory
belongs to the Outer Dinarids, the rocks of which originated - from the paleogeo-
graphic point of view - on the Dinaric carbonate platform. In the narrow tectonic
division this territory makes part of the Materija anticline. The axis of the anticline is
directed NW-SE and plunges northwest under a modest angle. In its northern part
where profiles 2 (NE of Materija) and 3 (Slivje) are sited, the Cretaceous and the
Paleogene beds dip 10 to 30° northeast. In the surroundings of Kozina where profile
1 is sited on the crest of the anticline, the beds dip 40 to 50° west. In the area between
Kozina and Slavnik they beds dip steeper southwest; the reach vertical or even
overturned position and are scaled in places.
The investigated territory is affected by rare faults. An important fault directed
NW-SE runs northeast of Kozina. The same fault can be followed also north of
Materija and Markovščina. Along this fault a horizontal slip for about 1,200 m
displaced the Paleogene and the Cretaceous beds northeast of Materija. A shorter
horizontal displacement can be seen also in Kozina close to profile 1.
The region shows a typical karst topography characterized by numerous dolines.
Deep reaching solution weathering which took place especially during the Pleisto-
cene caused the development of subterraneous river systems.
Stratigraphy
The problem of the Cretaceous-Tertiary boundary in the West Dinarides was first
studied by the Austrian geologist Stäche in the years 1859 to 1889. He introduced
the term "Liburnian stage" for the limestone beds which were deposited, according
to him, between the uppermost Cretaceous and the lowest Tertiary. The "Liburnian
stage" he divided into Lower foraminiferal limestones, Kozina beds and Upper
foraminiferal limestones (Stäche, 1889).
Instead of "Liburnian stage", Pavlovec and Pleničar (1979) proposed the
term "Liburnian formation", since, they argued, the sequence of the beds really
extends through several stages. The same authors regard the Lower foraminiferal
limestones (which they named "Vreme beds") to be of Maastrichtian age (Pavlovec
& Pleničar, 1979), the Kozina beds to be of Lower Paleocene age (Danian) and the
Upper foraminiferal limestones (named "Miliolid limestones") to be of Thanetian
age. Overlying the Miliolid limestones the so-called Alveolina-Nummulites limesto-
nes occur. They belong to the Ilerdian and Cuisian (Drobne & Pavlovec, 1979).
Regarding the proposal of a new division of the Paleogene beds (Ca vel i er
Microfacies analysis of limestones from the Upper Cretaceous
353i
Fig. 1. Schematic profile displaying the stratigraphie
units of the studied area
& P o m e r o 1, 1986) in which the Ilerdian is placed into the Upper Eocene and hence
lowering the Paleocene-Eocene boundary, the investigated beds can be stratigraphi-
cally ranged as follows: the Kozina limestone belongs to the Lower Paleocene or the
Danian respectively, the Miliolida limestone to the Upper Paleocene or the Thanetian
and the Alveolina - Nummulite limestone to the Lower Eocene (Fig. 1)
The carbonate sequence is overlain by clastic series (flysch) - not analized in this
paper - considered to be of Middle Eocene age.
The Vreme beds are not present in the studied localities. Instead, Cretaceous rocks
here are constituted by rudistid and micritic limestones which we take to have
formed during the Turonian and Senonian. The schematic profile (Fig. 1) shows the
stratigraphie units dealt with in the present paper. As we shall discuss later, the
stratigraphie subdivision of the Tertiary also reflects important changes of facies. It
should be pointed out, however, that the transitions between the carbonate units
within the Tertiary sequence are far from being abrupt.
354 i
David Delvalle & Stanko Buser
Description of localities
Profile 1   Kozina
The samples of profile 1 were collected from an exposure located about 15 km SE
from Trieste on the road that leads from Kozina to Koper (Figs. 2 and 3). On the
eastern side of the road, leading towards southwest, the whitish-grayish limestones
of Upper Cretaceous age can be observed. They are highly jointed in such a regular
way that the jointing can at first sight be confused with bedding planes. The
limestones here are constituted by alternating calcarenites and calcirudites. They
contain abundant remains of rudists and echinoids. The rocks show in some places
a brownish-reddisch color indicating the influence of bauxitization. Local brecci-
ation textures can be observed. The cementing agent is constituted of calcareous and
bauxitic material of yellowish color.
On the eastern side of this road cut it can be clearly seen how a 3 m thick bauxite
pocket separates the light colored Cretaceous limestones from the darker Paleocene
beds. Unfortunately, it is not possible to observe the boundary on the western side
because the place is overcast.
The Lower Paleocene strata (Kozina limestones) are well bedded having indivi-
dual thicknesses between 20 and 70 cm. They are concordant to the Upper Cretaceo-
ous strata indicating a parallel unconformity. The general direction of dip is W to
SW. The Kozina limestones are bituminous and rather poor in fossils. In some places
they bear remains of charophyta and gastropods. Pisoids can be locally recognized.
Bioturbation and brecciation fabrics, as well as local laminations are commonly
observed. The thickness of the Kozina limestones in this road cut totals 61m.
Fig. 2. Position of the investigated profiles in the Paleogene beds of the surroundings of Kozina
Microfacies analysis of limestones from the Upper Cretaceous
355i
Fig. 3. Geological setting the studied profils
Profile 2   NE from Materija
The sampling of profile 2 was carried out on hill Greben located 1.7 km NE from
Materija village (Figs. 2 and 3). The Upper Cretaceous beds are constituted of light
colored micritic limestones that show the effects of paleokarst. Scattered rudist
shells can be found. Like in profile 1 brecciation textures can be locally observed.
Again, the cementing material is calcareous and bauxitic. Minor local bauxite
intercalations are also present.
The contact between Cretaceous and Tertiary limestones can be readily recogni-
zed since the rocks show conspicuous differences in color. Also, the boundary is
characterized by an irregular paleorelief exhibiting former solution cavities. These
cavities were filled up with dark Lower Paleocene sediments. In profile 2 the Kozina
limestones have very much the same apperance as in profile 1. In comparison to the
Upper Cretaceous limestones they are obviously the better soil builders as can be
seen from the terrain morphology. The beds contain remains of charophyta and
356 David Delvalle & Stanko Buser
gastropods. Again, they have a rather high bitumen content. Although the transition
to the next unit, the Miliolid limestones, is rather indistinct, a thickness of about 20 m
can be assumed for the Kozina limestones. The Miliolid limestones are characterized
by their remarkable content of miliolid foraminifera. They show a slightly lighter
color than the Kozina limestones and are about 16 m thick.
Overlying the Miliolid limestones, the Alveolina-Nummulites limestones can be
distinguished, especially due to their content of these foraminifera and their light
gray color. Appreciable amounts of red algae (Lithothamnium) can be locally obser-
ved. The Alveolina-Nummulites limestones are quite rich in fossils, exclusively of
marine organisms.
Profile 3   Slivje
Profile 3 is located on the northern side of the road that leads from Markovščina
to Slivje (Figs. 2 and 3). Like in profile 2, the Upper Cretaceuos beds are light colored
and micritic. Only isolated rudist shells can be found. The limestones are well bedded
and show local laminations. The general direction of dip is northeast. The hiatus
between the Upper Cretaceous and the Paleocene beds increases from profile 1 to
profile 3. Again, fissure fillings consisting of bauxitic material can be observed. As
described in profile 2, the Cretaceous-Tertiary junction here is also marked by an
irregular paleorelief. The limestones belonging to each system can also be readily
distinguished by their contrasting colors (plate 7/1).
The Kozina limestones at the basis of the Tertiary sequence show bioturbation
and brecciation fabrics. Frequent components are remains of gastropods and charo-
phyta. The thickness of this unit here totals about 73 m.
Overlying the Kozina limestones the Miliolid limestones occur showing for the
most part the characteristics mentioned already in profile 2. As one follows the
vertical sequence into the younger layers, the gradual dominance of marine orga-
nisms, such as echinoids, corals, red and dasycladacean algae can be noticed. The
Miliolid limestones in this profile are approximately 47 m thick.
They are overlain by the Alveolina-Nummulites beds, the transition being diffuse.
This unit consists of light gray limestones containing these foraminifera as main
constituents and marine organisms such as bryozoa, echinoids and red algae.
Unfortunately, the sampling could not be carried out until reaching the flysch
series, which did not allow examination of the boundary between Alveolina-Num-
mulites limestones and flysch.
Methods
David Delvalle
A total of 154 samples was collected from the localities described above. All
samples were cut at right angles to bedding planes, and the more suitable halves were
selected for the preparation of acetate peels according to the method described by
McCrone (1963). The remaining material was ground and kept for mineralogical
and geochemical analysis.
Acetate peels were examined with a microfiche reading device which allowed
a maximal 42-fold enlargement and proved to be most useful for observation.
Thin sections were made from selected samples in order to solve special problems
such as recrystallization, cement types and optic orientation of crystals.
Microfacies analysis of limestones from the Upper Cretaceous 357
Mineral composition was determined by means of a Philips X-ray diffractometer
PW 1050/25 and a Siemens XRD 500.
Furthermore, determination of the trace elements Sr, Mg, Fe and Mn was carried
out with a Perkin Elmer Atomic Absorption Spectrophotometer, model 3030. The
long burner head and a mixture of acetylene and compressed air were used to atomize
the samples. The analysis of individual elements was carried out according to the
procedures described in the Perkin Elmer Analytical Manual.
The total carbonate content of the samples, later used to calculate the calcium
content, was measured with a device called »Karbonatbombe« designed by Müller
and Gastner (1971). Compared to other methods the Karbonatbombe proved to be
very reliable (Dunn, 1980).
Oxygen and carbon isotopie ratios were also determined for selected samples (9).
The nomenclature of Dunham (1962) with additions put forward by Embry
and Klovan (1972) were applied for rock classification. Moreover, description of
thin sections (see photoplates) was carried out by using also the Folk classification
(1959, 1962). Classification of primary limestone types according to the above
nomenclature was difficult or not possible at all in some cases because of post-
depositional texture alterations.
Results
Figures 4, 5 and 6 display the results of the pétrographie and trace element
analysis. Measured carbonate and calculated calcium contents are also included.
The column termed "texture" refers to features such as laminations, cross bed-
ding, stylolites and bioturbation.
No particular percentage limit was assumed in listing observed fossils. Listing
was rather carried out on the basis of sole recognition and it is not intended to
express quantities.
Although isotopie analyses were performed on samples of all three profiles,
results are best represented in the diagrams from profile (Figs. 7 and 8), and are thus
discussed there. The data of the other profiles, however, are fundamentally the same.
Profile 1   Kozina
The Upper Cretaceous limestones in this profile are constituted by light colored
wackestones to packstones and packstones to floatstones containing echinoid and
rudist remains. Gradual transitions between rock types are common, even within the
same horizon. Almost all studied samples showed clotted structure ("structure
grumeleuse", Cayeux, 1935, 271), as well as local extensive recrystallization.
Echinoid fragments generally exhibit well developed rim cement.
The single floatstone to rudstone found (sample no. 7) exhibits rounded intra-
clasts ("grapestones") in addition to rudist and echinoid fragments. Two cement
generations can be observed, however, the A cement is almost entirely obliterated
(plate 1/1).
The total carbonate content of the Upper Cretaceous limestones varies between 98
and 100 percent. Some samples (e. g. no. 6A and 11) show lower values due to the
influence of bauxitic material. Mg values oscillate between 1000 and 2000 ppm. The
remaining elements show rather low values: Sr (50 to 130 ppm); Mn (up to 40 ppm);
Fe (30 to 70 ppm).
358i
David Delvalle & Stanko Buser
Microfacies analysis of limestones from the Upper Cretaceous
3591
Fig. 4. Profile 1
The sample collected from the bauxite pocket shows a texture type which
Carrozi (1960) termed "oolitic". Individual ooids exhibit diameters up to 0.5mm,
reveal a brown-reddish color under the microscope and are clearly zoned. Such ooids
formed, of course, diagenetically (plate 1/4).
Sample no. 10, also collected from the pocket, has a rather conglomeratic fabric.
The rock fragments are constituted by limestones exhibiting rounded micritic bodies
("glaebules") cemented with microspar (plate 1/5).
At the basis of the Tertiary sequence the Kozina limestones occur consisting of
dark bituminous mudstones to wackestones, wackestones to packstones and packsto-
nes that underwent, however, local post-depositional texture alterations. Most sam-
ples contain abundant peloids, remains of charophyta (oogonia and gyrogonites),
blue-green algae and sparse minute ostracods. Important features of these limestones
360 David Delvalle & Stanko Buser
are clotted micrite, bioturturbation and breacciation fabrics, as well as laminations
(Fig. 4).
Mollusc shells are rather thin and sometimes bored.
Sample no. 19 was collected from a layer constituted by a limestone showing
intraclasts and peloids which can be distinguished from the surrounding matrix by
differences in color. Furthermore, tiny tooth-like crystals, arrayed along straight
lines, are scattered in the matrix. These crystals we believe to be calcite pseudo-
morphs after gypsum (plate 2/1).
Gastropods are locally abundant components of the Kozina limestones. Stäche
(1889) described two species which he named Cosinia and Stomatopsis. Schubert
(1912, 37) also mentioned the occurrence of various fresh watter and land gastropods.
Foraminifera are very small and sparse.
The microproblematicum Microcodium can be locally found in the shape of small,
regular calcite prisms (e. g. samples no. 48 and 50). Later on, we will discuss this
structure in some detail.
There is strong evidence pointing to the episodic (?) formation of calcareous crusts
(caliche) within the Kozina strata. For instance, samples 48 and 49 show incipient
alveolar texture (Esteban, 1974), as well as "flower spar" cement which is "parti-
cularly characteristic of calcareous crusts" (James, 1972, 826). Sample no. 50
contains characteristic caliche pisoids exhibiting circumgranular and intragranular
cracking (plate 3/3). Some of the observed brecciation textures probably resulted
from diagenetic processes inherent to calichification.
The Kozina limestones are characterized by their poor content of organisms
belonging to a limited number of species. They have rather high carbonate contents
(95 to 100 percent).
All XRD diagramms showed calcite as single carbonate phase.
Mg values remain around 2000 ppm and are seldom higher than 3000 ppm. Sr
content at first varies between 150 and 450 ppm and becomes continuously lower
until reaching a minimum in sample no. 61 (59 ppm). The element Mn shows
oscillating values between 20 and 40 ppm. An exception is sample no. 22 with
a maximum value of 141 ppm. The Fe content stays around 150 ppm. However, high
values were also recorded (samples no. 18, 19, 20, 38, 49 and 50, having respectively
221, 253, 191, 194, 224 and 289 ppm).
Profile 2   NE from Materija
The Upper Cretaceous limestones of profile 2 are constituted by whitishgrayish
wackestones, in places changing to packstones and floatstones (Fig. 5). Rudist shells
are not as common as in the profile 1. Frequent components are foraminifera
(miliolids, rotalids, orbitolinids), echinoid fragments and algae (Thaumatoporella
parvovesiculifera). Furthermore, locally abundant tiny, round to elliptical objects
can be observed which we take to be planktonic foraminifera of the species Pitho-
nella (plate 4/2).
Miliolids are rather small and often show recrystallized tests.
The limestones are occasionally brecciated (e.g. samples no. 2 and 6K). Such
breccias can be clearly observed, even with the microscope (microbreccia). The
fissures are not always cemented with sparite but partly filled with micritic and
siltsized material (plate 4/3).
In general, the limestones have a micritic matrix showing recrystallized areas.
Microfacies analysis of limestones from the Upper Cretaceous
361i
Explanation of figs. 4, 5 and 6
Moreover, the matrix of some samples contains scattered siltsized grains. Stylolites
can be locally observed.
The total carbonate content varies between 98 and 100 percent. Calcite appears in
the XRD diagramms as single carbonate phase. Mg values remain around 1000 ppm.
Sr shows very low values (between 50 and 90 ppm). Mn content stays almost constant
around 8 ppm, whereas Fe content averages 50 ppm.
As already stated in the above description of profile 2, the Upper Cretaceous
limestones are directly and concordantly overlain by the Kozina limestones.
The boundary between Cretaceous and Tertiary is marked by irregular relief
showing in places former deep reaching solution cavities. Microscopic observation of
362!
David Delvalle & Stanko Buser
Microfacies analysis of limestones from the Upper Cretaceous
363
Fig. 5. Profile 2
the contact reveals that it is overprinted by stylolites. The Kozina limestone at the
contact is constituted by a mudstone showing calcified filaments of an indefinite
origin (calcified root filaments ?). Siltsized grains are scattered in the matrix.
Only a slight decrease of СаСОз content can be recorded in the corresponding
Upper Cretaceous and Paleocene rocks present at the boundary (from 100 to 98
percent). Furthermore, with the exception of Mg (1170 to 960 ppm), the content of
remaining elements increases: Sr from 80 to 120 ppm; Fe from 60 to 110 ppm; Mn
from 4 to 12 ppm.
Profile 2 - unlike profile 1 - covers all three limestone units mentioned in sec-
tion 3.
The Kozina limestones have quite the same appearance as described in profile 1,
showing, however, an even lower fossil content. They are constituted by dark
bituminous mudstones, mudstones to wackestones, wackestones and wackestones to
packstones (Fig. 5).
Most common components are peloids. Gastropods are not as frequent as in
profile 1 but when present, they show micritic envelopes. Again, common features are
bioturbation and brecciation textures (plate 5/1).
A gradual transition leads to the Miliolid limestones which show the following
miliolid species (Drobne, 1974): Idalina, Periloculina and Fabularia, as well as
conical forms like Fallotella, Coskinolina and other. Moreover, foraminifera with
discoidal shapes (Broeckinella, Discocyclina) have been also reported (Drobne,
1979). According to Drobne and Pavlovec (1979), first alveolinids appear in the
upper part of the Miliolid limestones (Glomalveolina primaeva).
As pointed out before, a gradual dominance of typically marine organisms can be
ascertained the younger the beds get. Such organisms include dasycladacean algae,
364 David Delvalle & Stanko Buser
red algae (Lithothamnium), echinoid fragments and large foraminifera. Dasyclada-
cean algae and gastropod shells are usually recrystallized. Other common constitu-
ents are peloids (plate 5/2).
Miliolid limestones consist of wackestones, wackestones to packstones and poorly
washed packstones (Fig. 5).
A characteristic feature of the Alveolina-Nummulites limestones overlying Mili-
olid limestones is their content of strictly marine organisms. Along with large
foraminifera (alveolinids, nummulitids, discocyclinids etc.), bryozoa, red algae (Li-
thothamnium), echinoid and sponge fragments occur (plate 5/3). According to
Drobne and Pavlovec (1979) in the Golež section near Kozina 29 species of
alveolines and 13 of nummulites have been determined.
In certain places remains of Lithothamnium can be quite abundant (samples no.
20 and 21). Peloids - being perhaps in part small intraclasts - are also present.
The total carbonate content shows a clearly increasing tendency towards the
Alveolina-Nummulites limestones where it reaches 100 percent values. Calcite was
determined as single carbonate phase.
Within the Kozina limestones Sr values show an increasing tendency, reaching
a maximum in sample no. 12 (532 ppm). Thereafter, values drop gradually towards
Miliolid and Alveolina-Nummulites limestones reaching a minimum in sample no. 22
(104 ppm). Mg values also increase continuously towards Miliolid limestones reac-
hing a maximum value in sample no. 14 (4500 ppm) and then dropping towards
Alveolina-Nummulites limestones (minimum: 830 ppm in sample no. 22). Mn content
varies rather irregularly between 10 and 35 ppm. Fe values also show irregular
variations between 40 and 150 ppm. However, highest contents occur within Kozina
limestones.
Profile 3   Slivje
Compared to corresponding strata in the other profiles the Upper Cretaceous
limestones of profile 3 (Fig. 6) have the lowest fossil content. With one exception
(sample no. 4) the limestones consist of light colored mudstones and mudstones to
wackestones. The following fosils were observed: small foraminifera (miliolids and
other), algae (Thaumatoporella), and isolated rudist and echinoid fragments. Sample
no. 4 was collected from a bed constituted by floatstone.
The limestones usually show clotted structure. Laminations, sometimes associ-
ated with fenestral fabrics, can be observed (e. g. sample no. 5). Rudist shells are
rather small and, especially near the boundary, completely recrystallized.
Occasionally, rudist shells filled with micritic material can be encountered (inter-
nal sediment). Recrystallized areas are present, however, as in sample no. 6, not
affecting lamination. This same sample also contains scattered bauxite ooids.
Thaumatoporella algae sometimes exhibit geopetal fabrics. Miliolids are small
and have often recrystallized shells.
Small and irregular bauxite intercalations can be found within the Upper Creta-
ceous limestones. From such an intercalation sample no. 3 was collected. It has oolitic
texture and is composed of the minerals boehmite, goethite, kaolinite, and anatase, as
the XRD diagram shows (see figure 7).
The total carbonate content varies between 98 and 100 percent. XRD diagrams
indicate calcite as single carbonate phase.
Mg values oscillate at first around 1000 ppm, increasing suddenly, before reac-
hing the boundary, to 3400 ppm. The analysis of Sr results in similar evidence, the
Microfacies analysis of limestones from the Upper Cretaceous 365
values varying at first around 100 ppm and then increasing to 230 ppm. Mn content
remains around 13 ppm, whereas Fe content varies between 60 and 200 ppm.
The Cretaceous-Tertiary boundary in profile 3 - like in profile 2 - is easily
recognized since the corresponding rocks show conspicuous differences in color. The
junction here is also marked by a paleorelief with sharp edges and former solution
cavities (plate 7/1).
The content of all trace elements increases immediately beyond the contact: Mg
from 3400 to 3900 ppm; Sr from 335 to 470; Mn from 11 to 25 ppm and Fe from 60 to
230 ppm.
The Kozina limestones of this profile are constituted by dark bituminous mudsto-
nes, wackestones and packstones. There are sometimes gradual transitions between
these limestone types. The rocks contain gastropods, charophyta remains and minute
ostracods. Burrows and brecciation fabrics are frequent.
An outstanding feature of the Paleocene strata of profile 3 (including Miliolid
limestones) is the occurrence of Microcodium. It appears as loose, regular calcite
prisms but also forms organized arrangements (plate 6). Klapp a (1978) termed the
first "Microcodium grains", whereas he named the second "Microcodium aggrega-
tes".
Brecciation and alveolar textures are very common in the Kozina strata (plate 7/2).
Peloids are quite abundant in the Paleocene limestones often forming packstones.
Miliolid limestones consisit of mudstones, wackestones to packstones and packstones
to grainstones. The latter contain fossils of various species which evidently accumu-
lated by current action after death (plate 6/3). Such biocalcarenites also show cross-
bedding (e.g. sample no. 41).
In the younger Miliolid strata remains of marine organisms gradually predomi-
nate. Among these, there are echinoids, corals, dasycladacean algae (see also Buser
& Radoičić, 1987), coralline algae and sponge fragments.
Exhibiting a characteristic facies, the Miliolida limestone is ubiquitous all over
the Karst region and appears in all profiles. It probably did originate in a specific
environment. Consequently, it has been separated as a special formation and named
the Slivje formation after a so named village. The footwall of this formation is in the
investigated area the Kozina limestone; it does constitute the upper part of the
Liburnian formation, whereas its hanging wall beds are the Alveolina-Nummulite
limestones. The characteristic profile of the Slivje formation is exposed in a road-cut
west of Slivje, where samples were taken for our investigations.
The Alveolina-Nummulites limestones of profile 3 are constituted by light gray
wackestones to packstones containing - in addition to these foraminifera - red algae,
bryozoa, echinoid fragments and peloids (plate 6/4). Red algae can be locally more
important constituents than alveolines and nummulites (e.g. samples no. 64 and 65).
Sometimes these algae are found incrusting other organisms like bryozoa.
With a few exceptions (e.g. sample no. 27 with 94 percent), the total carbonate
content of Kozina and Miliolid limestones varies between 98 and 100 percent. On the
average, however, the highest carbonate values were recorded in the Alveolina-
Nummulites limestones.
Kozina limestones have varying Mg (1800 to 4850 ppm) and Sr content (125 to 470
ppm). Fe and Mn content oscillates between 42 and 230 ppm and between 10 and 37
ppm, respectively.
The highest content of trace elements was measured right at the basis of the
Tertiary sequence.
366i
David Delvalle & Stanko Buser
Microfacies analysis of limestones from the Upper Cretaceous
367
368;
David Delvalle & Stanko Buser
Microfacies analysis of limestones from the Upper Cretaceous
369 i
Fig. 6. Profile 3
370Î
David Delvalle & Stanko Buser
Fig. 7 XRD - diagram showing the mineralogical composition of bauxite
k = kaolinite; g = goethite; b = boehmite; an = anatase
Miliolid limestones show distinctly higher Mg (2570 to 4850 ppm) and Sr content
(223 to 723 ppm). Fe and Mn content varies between 36 and 266 ppm and between
9 and 64 ppm respectively.
Alveolina-Nummulites limestones have the following trace element content: Mg
2250 to 3910 ppm; Sr 213 to 263 ppm; Fe 37 to 53 ppm and Mn 9 to 45 ppm. These are
the highest and lowest values registered.
Figures 8 and 9 display the results of the isotopie analysis (b^^C and б'**0) which
were carried out for the following samples: 6, 7K (Upper Cretaceous limestones); 7T,
12, and 15 (Kozina limestones); 34 and 46 (Miliolid limestones); 63 and 66 (Alveolina-
Nummulites limestones).
The ô'^C diagram (Fig. 8) shows that samples no. 46, 63 and 66 correspond to
marine carbonates which formed under isotopie equilibrium with atmospheric car-
bon dioxide. In arrow direction, however, fresh water influence becomes more and
more noticeable, as indicated by the negative б'-^С values. Fresh water input may have
taken place simultaneously with deposition (brackish environments) and/or during
subaerial exposure, where soil forming and subaerial diagenetic processes were
active.
Microfacies analysis of limestones from the Upper Cretaceous
371
Fig. 8. Ò^^C - values of limestones from profile 3 plotted against the thickness at which the
samples were collected
The Upper Cretaceous limestones shov^^ a more positive value than the ones
determined in samples from the basis of the Tertiary sequence. Nevertheless, these
values do not correspond to those of normal marine carbonates. It can be expected
that isotopie exchange between cements and meteoric waters - where the lighter
isotopes predominate - took place during karst development.
The б'**0 diagram (figure 9) shows two areas. The values within area A are less
negative than those in area B. Although they do not actually correspond to carbona-
372
David Delvalle & Stanko Buser
Fig. 9. Ô'^O - values of limestones from profile 3 plotted against the
thickness at which the samples were collected
tes formed under normal marine conditions, they do document a tendency towards
characteristic values of marine carbonates. In contrast, area B shows values that
distinctly indicate fresh water influence.
Palynological analysis
The following samples were selected for palynological analysis: 13, 14, 15 (profile
1); 6K, 6T, 9 (profile 2); 7, 8 (profile 3). Only two of these samples, no. 13 and no. 8,
yielded well preserved sporomorph species that allowed sure determination.
Microfacies analysis of limestones from the Upper Cretaceous 373
None of the samples contained enough material to permit a quantitative statisti-
cal analysis which is necessary when characteristic time species are absent. Nevert-
heless, some statements concerning stratigraphy can be made.
For instance, characteristic Cretaceous and Paleocene sporomorphs were not
found.
Table 1 displays the determined species. The supposed botanic origin is given in
parentheses.
Beside some forms that reach into the Mesozoic (disaccate conifers, pinus forms),
most sporomorphs are rather typical for the Eocene and the Miocene. Almost all
detected forms appear sooner or later during the Eocene and last until the Upper
Miocene, and partly the Pliocene.
Sample no. 8, for example, contained the unmistakable pollen of Pterocarya
which appeared in the Middle Eocene and attained its maximal distribution between
the Upper Oligocene and the Upper Miocene, partly the Pliocene and locally until the
Lower Pleistocene.
Polyporopollenites undulosus (Ulmus, Zelkova) also reach from the Eocene to the
Pleistocene, having its maximal distribution since the Oligocene.
Table 1. List of the determined sporomorphs
Sample no. 8 (profile 3)
Sequoiapollenites polyformosus? (Sequoia)
Pityosporites labdacus (Pinns)
Poly por opollenites undulosus (Ulmus, Zelkova)
Pterocaryapollenites stellatus (Pterocarya)
Inaperturopollenites dubius (Taxodium, Glyptostrobus)
Trivestibulopollenites betuloides (Betula)
Caryapollenites simplex (Carya)
Fungus spores, not well preserved plancton, algal filaments
Sample no. 13 (profile 1)
Pityosporites labdacus (Pinus)
Porocolpopollenites vestibulum (Symplocos)
Sciadopityspollenites serratus (Sciadopitys)
Tricolporopollenites marcodurensis I satzveryensis (Partenocissus I Cornus)
Nyssapollenites kruschi (Nyssa)
Triatriopollenites microcoryphaeus (Platycarya, Engelhardtia)
Pityosporites microalatus (Pinus? Cathaya)
Leiotriletes maxoides (Lygodium)
Polyporopollenites undulosus (Ulmus, Zelkova)
Leiotriletes spec. (Lygodium)
Inaperturopollenites dubius (Taxodium, Glyptostrobus)
Intratriporopollenites instructus? (Tilia)
Pollen remains of disaccate conifers, algal remains
Sample no. 14 (profile 1)
Polyvestibulopollenites verus (Alnus)
Algal remains
Sample no. 6K (profile 2)
Pollen remains of disaccate conifers
Algal remains
The remaining samples (no. 7, 6T, 15 and 9) contained indeterminable spores
374 David Delvalle & Stanko Buser
Facies interpretation
Upper Cretaceous rocks
The Upper Cretaceous floatstones from profile 1 probably correspond to accumu-
lated debris from former rudist mounds. Rudist and echinoid fragments contained in
these limestones are angular indicating short transport or none at all. Moreover, the
limestones exhibit clotted structure which is generally indicative of low energy
environments. However, at least temporal energy increases are suggested by the
presence of an intrabiosparite interlocking the floatstone (sample no. 7, plate 1/1).
Intraclasts are constituted by grapestones which form, according to Flügel (1978,
109), within the subtidal to intertidal zones of a shallow water environment with
little water circulation.
The Upper Cretaceous limestones of profiles 2 and 3 show a higher volumetric
micrite content than corresponding rocks of profile 1. Rudist and echinoid fragments
are more rare. The dominating organisms here are miliolids, the alga Thaumatopo-
rella and planktonic foraminifera. Although the latter are rather numerous, they are
most probably allochthonous. Local laminations likely associated with both peloids
and blue-green algae are present (e.g. sample no. 6 from profile 3).
Low energy conditions are indicated - in addition to micrite dominance - by the
locally found clotted structure. Furthermore, the observed miliolids are very small
and thin-shelled.
Microfacies data of the Upper Cretaceous limestones suggest a warm-water
shallow open shelf with relatively small rudist mounds.
Bauxite ooids are accessory constituents of the Upper Cretaceous limestones.
Since this bauxitic material is obviously penecontemporaneous to sediment deposi-
tion, it can be concluded that the bauxitization took already place in Upper Cretace-
uos time. Furthermore, bauxitic material in these limestones indicates land proxi-
mity.
The observed bauxite pocket shows a conglomeratic fabric which is indicative of
redeposition. The rock fragments contained in it belong to limestones showing
glaebules and incipient crumbly fracturing (plate 1/5). These features have been
observed in caliche hardpans, thus pointing to its occurrence in hinterland. This
seems plausible since "the soil cover of karst may also evolve in the direction of
The uncertain Intratriporopollenites instructus (Tilia) does not seem to appear
before the Upper Oligocene.
To summarize, the following remarks are pertinent:
- An accurate stratigraphie statement is not possible because characteristic time
sporomorphs are lacking. Moreover, a quantitative statistical analysis could not be
carried out.
- The detected sporomorphs do point, however, to a time period somewhere between
the Eocene and the Pliocene.
It should be pointed out that the corresponding flora may have appeared earlier in
the Mediterranean region than it is generally believed.
The lack of dinoflagellate cysts excludes the possibility of deposition under
marine conditions. Furthermore, plant remains were often observed.
Microfacies analysis of limestones from the Upper Cretaceous 375
carbonate rich soils of the caliche type, particularly in mature and late stages of karst
evolution" (Esteban & Klappa, 1983, 14).
After a long cessation of sedimentation which extended until the end of Upper
Cretaceous time the Kozina limestones started to form at the beginning of the
Tertiary age.
Kozina limestones
Facies interpretation of these sediments is difficult because of their polygenetic
character. According to Pavlovec and Pleničar (1979), these bads show "quick
exchanges of lagoonal, brackish, lacustrine and partly marine facies" (p. 28). Grü-
ble (1980, 41) referred to the Kozina limestones as limnic and estuarine sediments.
The encountered facies diversity is attributed to tectonic movements which took
place at sedimentation time.
The criteria pointing to a lacustrine origin of the Kozina limestones are essentially
paleontological. Frequent remains of charophyta, blue-green algae, gastropods, mi-
nute ostracods and thin lamellibranch shells constitute the rather poor flora and
fauna remains of these beds.
Limitation of species could be, theoretically, caused by frequent climatic changes
to which lakes are sensitive (Collinson, 1978, 67). However, low organism diver-
sity is in the first place the result of stress conditions which can be found in other
environments (see Picard & High, 1972, 117).
Flügel (1978, 67) pointed out that charophyta are useful fresh water indicators.
Nevertheless, some species seem to tolerate salinity variations up to 18 and 26 parts
per thousand (Heckel, 1972, 277), and other can be even found in hypersaline
milieus (Flügel, 1978, 265). Charophyta can thus be found in various habitats
(compare Johnson, 1961, 36).
The Kozina limestones show high carbonate contents, varying mostly beetween 95
and 100 percent. The lack of any significant clastic component indicates that the
depositional setting was, at least in the studied area, not fed by any river. Moreover,
no fluvial series are known from the region. This is an important argument against
the suggested estuarine origin of the Kozina limestones, all the more so as estuarine
sediments show particular characteristics that cannot be compared with the ones
observed (see Elliot, 1978, 171 ff.).
According to Picard and High (1972) the association of supposed lacustrine
beds with fluvial sediments can be (also) important to distinguish between lacustrine
and lagoonal environments. The same authors add: "If the unknown unit is in close
proximity with marine rocks, and no intervening fluvial rocks are present, a lagoonal
setting that opens to the sea is indicated" (p. 117).
This is of particular importance since we know that the transition to the next unit
(Miliolid limestones) is gradual, and that the predominance of marine organisms is
more and more conspicuous the younger the sequence gets.
Kozina limestones are predominantly micritic, a fact that is generally indicative
of low energy environments. The rocks are typically dark and bituminous pointing to
deposition under euxinic conditions. These were probably caused by restricted water
circulation. Such restricted environments can develop as brackish water, anoxic
swamps or as hypersaline shelf basins (see E nos, 1983, 281).
In several samples dissaminated aggregates of Microcodium were detected. Ac-
cording to Klappa (1978,510), Microcodium is the result of calcification of mycorr-
hizae, a symbiosis between fungi and the cortical cells of higher plant roots. Since
376 David Delvalle & Stanko Buser
soil is the natural environment in which plants grow, Microcodium is ultimately
indicative of pedogenetic processes. Furthermore, Esteban (personal communica-
tion) stated that rather typical environments for the formation of Microcodium are
hydromorphic soils, meaning water-saturated sediments subjected to incipient soil
processes. Such environments may be found in palustrine areas (swamps, marsh).
Indeed, Microcodium has been reported from palustrine milieus (Freytet, 1971,
1973).
Another important feature of the Kozina limestones is the occurrence of calcite
pseudomorphs after gypsum. S ell wo od (1978) referred to gypsum formation in
marshes (supratidal zone) from subtropical carbonate shelves. Moreover, he adds,
interstitial gypsum crystals can also be found in mostly undisturbed algal mats from
the upper intertidal zone "where muddy sediment brought in by storms is trapped"
(p. 265). The textural characteristics of sample 19 from profile 1 strongly resemble
this situation (plate 1/1). Freytet (1973, 43) also reported calcite pseudomorphs
after gypsum from palustrine environments.
The observed bioturbation textures were probably not only caused by burrowing
organisms within the sediment but also by physical, chemical and biological distur-
bance of the soil material during subaerial exposure ("pedoturbation"). A close
examination of the brecciation textures reveals that they may have originated in
various ways. As the result of reworking of lime mud material under subaqueous
conditions, the clasts may be angular to subrounded, coated or not, depending on the
lithification degree of the parent material. Some of the observed breccia, however,
may have been caused by pedoturbation (e. g. root penetration) or by diagenetic
processes (calichification).
The calculated carbon and oxygen isotopie ratios support the idea that the Kozina
limestones formed in a coastal palustrine area submitted to sea level and salinity
changes. During rather long periods of subaerial exposure, calichification followed
soil-forming processes as the accumulation of СаСОз increased in detriment of
porosity and permeability of the soil profile. Climatic factors also played an impor-
tant role, particularly in controlling rainfall and evaporation.
Not until the younger beds, a relative diversity of benthonic foraminifera can be
observed. These beds represent the gradual transition to the Miliolid limestones and
are constituted by poorly washed foraminiferal biosparites, indicating some water
circulation within thè deposition site. This slight increase in water energy allowed
some oxygenation creating better conditions for life to develop.
This should also be regarded as expression of the continuous trangressive deve-
lopment, since the limestone types observed in the Miliolid strata correspond to those
Wilson (1975) described as having formed within facies zone 8. Moreover, the
younger beds show a marked dominance of marine organisms which indicates that
the fresh water input gradually grew weaker. This assumption is supported by the
isotopie data.
Miliolid limestones - Slivje formation
Primary Miliolid limestone types are comparable to several standard microfacies
described by Wilson (1975), which indicate restricted conditions: peloidal packsto-
nes to grainstones containing f o. aminif era (SMF 16); grapestone-peloid-intraclast
grainstones (SMF 17); foraminiferal or dasyclad algal packstones to grainstones with
peloids (SMF 18); laminated to bioturbated pellet mudstones to wackestones, locally
with fenestral fabric (SMF 19).
Microfacies analysis of limestones from the Upper Cretaceous 377
Miliolid limestones also show horizons containing in situ formed Microcodium.
An alternative to the idea of periodic discontinuities which must have lasted long
enough to allow pedogenetic processes to take place is the conception of islands
(similar to modern mangrove islands) within the intertidal zone, which were coloni-
zed by higher plants. In the proximity of these islands channels occurred where
sediments formed exhibiting diverse depositional textures. Texture diversity is
probably due to the fact that current velocity within channels may vary greatly, thus
causing the lithologie spectrum to range from mudstones to grainstones (compare
Sellwood, 1978, 266). Moreover, analogous to some modern environments, bars
may occur within the channel system showing cross-bedded sediments. Such a sedi-
ment could be recognized in sample no. 41 from profile 3 (grainstone). It contains
gastropods, dasycladacean algae, miliolids, corals and echinoid remains, peloids and
grapestones.
Organism diversity in the Miliolid limestones indicates favorable living conditi-
ons. Surely, some of the observed organisms were not buried in the place they lived
on. Particularly in the case of the biocalcarenites, probably most organisms accumu-
lated by current action. Nevertheless, especially in the younger beds of the Miliolid
limestones, biota abundance indicates a gradual disappearence of stress conditions
which were perhaps determined by strong variations in salinity and/or poor water
circulation.
A gradual transition also exists between Miliolid and Alveolina-Nummulites
limestones simultaneously indicating a gradual change of facies.
Alveolina-Nummulites limestones
The encountered limestones obviously formed in the subtidal zone of a well
oxygenated, strictly marine area of the carbonate platform. The presence of frequent
organisms such as coralline algae and bryozoa point to the proximity of reefs.
Furthermore, their rather high carbonate content and light color indicate off-shore
deposition lacking significant clastic and organic residues.
The depositional setting of the Alveolina-Nummulites limestones can be probably
compared with the one assumed for similar fossil strata from the Mediterranean
region. An extended open carbonate platform with a more or less horizontal sedimen-
tation basis has been suggested (see Cita, 1965, 39; Wilson & Jordan, 1983,
316-317).
Isotopie and paleontological data point to marine conditions.
Depositional history and concluding remarks
During the Mesozoic a typical shallow water carbonate sedimentation took place
on the Dinaric carbonate platform (Buser, 1989).
As suggested by the occurrence of bauxitic ooids in the Upper Cretaceous
limestones, the sea began to retreat from the platform in Upper Cretaceous time
already.
The regressive development was caused by the tectonic uplift of the Dinaric plate
which is generally associated with the Alpine orogenesis.
Subaerial exposure was firstly characterized by karst development and bauxiti-
zation. Carbonate loss by dissolution was then followed by carbonate accumulation
during calichification.
378
David Delvalle & Stanko Buser
Fig. 10. Block diagram showing facial relationships between the studied units
Facies interpretation of the Paleocene strata (Kozina and partly Miliolid limesto-
nes) is difficult because we are dealing with polygenetic sediments. We suggest that
these sediments originated within a coastal zone submitted to sea level and climatic
changes. In this sense, the vertical sequence shows superimposed palustrine and
brackish lagoonal horizons that were altered by soil-forming processes and caliche
development.
It should be examined whether possibly overlooked fluvial series are associated
with the Kozina limestones, in which case a partly lacustrine origin could be
postulated.
The primary limestone types of the Miliolid limestones clearly formed within the
intertidal and subtidal zones, thus documenting the transgressive character of the
sequence. As we found Microcodium aggregates within the Miliolid limestones, this
may point either to prolonged emergence periods, or to the existence of emerged
areas (islands) that were colonized by higher plants.
Alveolina-Nummulites limestones clearly formed under subtidal conditions. The
sediments were deposited in a strictly marine, well oxygenated environment. This
indicates an important facies change, since restricted conditions gradually weake-
ned. At the same time, Alveolina-Nummulites limestones give evidence of the next
step in a transgressive development which finally culminated in the formation of
deep water sediments (flysch).
The low Sr and Mg contents of the Upper Cretaceous limestones correspond to
those commonly found in carbonate rocks affected by meteoric diagenesis. This is
also supported by the isotopie data (negative values).
Whereas Kozina and Alveolina-Nummulites limestones have comparable Sr and
Mg contents (average: 250 and 2600 ppm respectively), the content of these trace
elements is distictly higher in the Miliolid limestones (average: 420 and 4100). It
cannot be positively concluded whether these differences in content are related to the
former mineralogical composition of the carbonates (high magnesian calcite, arago-
Microfacies analysis of limestones from the Upper Cretaceous 379
Acknowledgements
The authors are greatly indebted to Dr. Reiner Botz (Institute of Environmetal
Physics. University of Heidelberg) who carried out the isotopie determinations, and
to Dr. Martin Hottenrott (Institute of Geology and Paleontology, University of
Gießen) who made the palynological analysis. The first author wishes to thank the
Deutscher Akademischer Austausch-Dienst (DAAD) for its financial support.
nite) and/or to diagenetic recrystallization. Mn and Fe values are rather low for all
units.
The block diagram (Fig. 10) integrates the three stratigraphie units which were
treated in this paper stressing their facies significance.
Finally, and in spite of its facies complexity, the analyzed sequence can be
regarded as a good example for the validity of Walther's Law which stated that the
vertical succession of facies in the rock record reflects lateral sequence in the
depositional setting (W a 11 h e r, 1894).
380 David Delvalle & Stanko Buser
References
Bignot, G. 1981, Illustration and Paleoecological Significance of Cretaceous and Eocene
Girvanella Limestones from Istria (Yugoslavia, Italy). In: Phanerozoic Stromatolites, Monty,
C. (ed.), 134-139, Springer, Berlin-Heidelberg-New York.
B u s e r, S. 1989, Development of the Dinaric and the Julian carbonate platforms and of the
intermediate Slovenian basin (NW Yugoslavia). Mem. Soc. Geol. It., 40 (1987), 313-320, Roma.
Buser, S. & Radoičić, R. 1987, Dazikladacejske alge u srednjopaleocenskim miliolid-
skim krečnjacima na Krasu u Sloveniji. Geologija, 28/29 (1985/86), 69-91, Ljubljana.
Carrozi A. V. 1960, Microscopic Sedimentary Petrography. Wiley & Sons Inc., 485 p., New
York-London.
Cavelier, C. & Pomerol, C. 1986, Stratigraphy of the Paleogene. Bull. Soc. geol.
France, (8), 2, 255-265, Paris.
Cay eux, L. 1935, Les roches sédimentaires de France. Roches carbonatées (Calcaires et
dolomies). Masson & Cie, 436 p., Paris.
Cita, M. B. 1965, Jurassic, Cretaceous and Tertiary Microfacies from the Southern Alps
(Northern Italy). Brill, 99 p., Leiden.
Collinson, J. D. 1978, Lakes. In: Sedimentary environments and facies, Reading, H.
(ed.), Blackwell, 61-79, Oxford-Edinburgh-Boston-Melbourne.
Delvalle, D. 1985, Mikrofazielle Untersuchung der Kreide/Tertiär-Grenze in NW Jugo-
slawien (Slowenien). Unveröffentl. Dipl. Arbeit, Universität Heidelberg.
Drobne, K. 1974, Les grandes Miliolides des couches Paléocènes de la Yugoslavie du
Nord-Ouest (Idalina, Fabularia, Lacazina, Periloculina). Razprave 4. razr. SAZU, 17/3,
125-184, Ljubljana.
Drobne, K. 1979,PaleoceneandEocenebedsof Slovenia and Istria. In: Drobne (ed.) 16''^
Europ. Micropal. Coll., 49-64, Ljubljana.
Drobne, K. & Pavlovec, R. 1979, Excursion K, Golež - Paleocene, Illerdian, Cuisian.
In: Drobne (ed.) 16'^ Europ. Micropal. Coll., 217-224, Ljubljana.
Drobne, K., Ogorelec, B., Pleničar, M., Zucchi-Stolf a, M. L. & Turnšek, D.
1988, Maastrichtian, Danian and Thanetian beds in Dolenja vas (NW Dinarides, Yugoslavia).
Mikrofacies, foraminifers, rudists and corals. Razprave 4. razr. SAZU, 29, 149-224, Ljubljana.
Dunham, R. 1962, Classification of Carbonate Rocks According to Depositional Texture.
In: Classification of Carbonate Rocks, Ham, W. (ed.). Amer. Assoc. Petrol. Geol. (AAPG),
memoir 1, 108-122, Tulsa, USA.
Dunn, D. 1980, Revised techniques for quantitative calcium carbonate analysis using the
"Karbonat-Bombe" and comparisons to other quantitative carbonate analysis methods. Jour.
Sed. Petrol, vol. 50/2, 631-637, Tulsa, USA.
Elliot, T. 1978, Clastic shorelines. In: Sedimentary environments and facies, Reading,
H. (ed.), Blackwell, 143-177, Oxford-London-Edinburgh-Boston-Melboume.
Embry, A. F. & Klovan, E.J. 1972, Absolute depth limits of late Devonian paleoecologi-
cal zones. Geol. Rdsch., 61, 672-686, Stuttgart.
Enos, P. 1983, Shelf. In: Carbonate Depositional Environments, Scholle, P., Bebout,
D. & Moore, C. (eds), AAPG memoir 33, 267-296, Tulsa, USA.
Esteban, M. 1974, Caliche textures and "Microcodium". Soc. Geol. Italiana Bull, (supp.),
vol. 92, 105-125.
Esteban, M. & Klappa, C. 1983, Subaerial Exposure Environment. In: Carbonate
Depositional Environments, Scholle, P., Rebout, D. & Moore, C. (eds), AAPG memoir 33,
1-54, Tulsa, USA.
Flügel, E. 1978, Mikrofazielle Untersuchung von Kalken. Springer, 454 p., Berlin-Heidel-
berg-New York.
Folk, R. 1959, Practical Pétrographie Classification of Limestones. In: Classification of
Limestones. Bull. Amer. Assoc. Petrol. Geol., vol. 43, 1-38, Tulsa, USA.
Folk, R. 1962, Spectral Classification of Limestones Types. In: Classification of Carbonate
Rocks, Ham, W. (eds), AAPG memoir 1, 62-84, Tulsa, USA.
Freytet, P. 1971, Les depots continentaux et marins du Crétacé Supérieur et des cauches
de passage à l'Eocène en Languedoc. Bull. Bur. Rech. Géol. Min. Sér. 2, sect. 1, vol. 4, 1-54.
Freytet, P. 1973, Petrography and paleo-environment of continental carbonate deposits
with particular reference to the Upper Cretaceous and Lower Eocene of Languedoc (Southern
France). Sed. Geol., vol. 10, 25-60, Amsterdam.
Grubi Ć, A. 1980, An Outline of Geology of Yugoslavia. In: Guidebook of the 26'^. Internat.
Geol. Congress, no. 15, 48 p., Paris.
Microfacies analysis of limestones from the Upper Cretaceous 381
Hamrla, M. 1960, K razvoju in stratigrafiji produktivnih liburnijskih plasti Primorskega
krasa. Rud.-metal, zbornik 3, 203-216, Ljubljana.
H e C k e 1, P. 1972, Recognition of Ancient Shallow Marine Environments. In: Recognition of
Ancient Sedimentary Environments, Rigby, J. & Hamblin, W. (eds), SEPM spec, paper Í 6,
226-286.
James, N. P. 1972, Holocene and Pleistocene calcareous crusts (caliche) profiles: Criteria
for subaerial exposure. Jour. Sed. Petrol., vol. 42, 817-836, Tulsa, USA.
Johnson, J. H. 1961, Limestone-Building Algae and Algal Limestones. Colorado School of
Mines, 297 p., Colorado, USA.
Klapp a, C. 1978, Biolithogenesis of Microcodium: elucidation. Sedimentology, vol. 25,
489-522.
McCrone, A. 1963, Quick Preparation of Peel-prints for Sedimentary Petrography. Jour.
Sed. Petrol., vol. 33, 228-230, Tulsa, USA.
Müller, G. & Gastner, M. 1971, The "Karbonat-Bombe", a simple device for the
determination of the carbonate content in sediment, soils and other materials. N. Jb. Min. H. 10,
466-469, Stuttgart.
Pavlovec, R. 1963, Stratigrafski razvoj starejšega paleogena v južnozahodni Sloveniji.
Razprave SAZU, 4. razr. 7, 421-556, Ljubljana.
Pavlovec, R. & Pleničar, M. 1979, Boundary between Cretaceous and Tertiary in the
limestone beds of the West Dinarides. Symp. Cret.-Tert. Boundary events, Copenhagen.
Picard, M. & High, L. 1972, Criteria for Recognizing Lacustrine Rocks. In: Criteria for
Recognizing Ancient Sedimentary Environments, Rigby, J. & Hamblin, W. (eds). SEPM,
spec, paper 16, 108-145, Tulsa, USA.
Pleničar, M. 1961, Stratigrafski razvoj krednih plasti na južnem Primorskem in Notranj-
skem. Geologija, 6, 22-145, Ljubljana.
Seilwood, B. 1978, Shallow-water carbonate environments. In: Sedimentary environ-
ments and facies, Reading, H. (eds). Blackwell, 259-313, Oxford-London-Edinburgh-Bo-
ston-Melboume.
Schubert, R. 1912, Geologischer Führer durch die nördliche Adria. Sammig. geol. Führer,
vol. 17. Gebr. Bomträger, 213 p., Berlin.
Stäche, G. 1889, Die Libumische Stufe und deren Grenz-Horizonte. Abh. geol. R. A., vol.
13, 170 p., Wien.
Walt her, J. 1894, Einleitung in die Geologie als historische Wissenschaft. Fischer, vol. 2,
195-531, Jena.
Wilson, J. L. 1975, Carbonate Facies in Geologie History. Springer, 471 p., Berlin-Heidel-
berg-New York.
Wilson, J. L. & Jordan, C. 1983, Middle Shelf. In: Carbonate Depositional Environ-
ments, Scholle, P., Bebout, D. & Moore, C. (eds). AAPG, memoir 33, 297-344, Tulsa,
USA.
382 David Delvalle & Stanko Buser
Plate 1
1 Sample 7
Poorly washed intrabiosparite (floatstone to rudstone)
An utterly recrystallized rudist shell showing internal sediment and micritized shell
structures. Rounded components are intraclastes ("grapestones") that probably formed
within the subtidal to the intertidal zones of shallow water environment with little water
circulation. The A cement has been completely obliterated during meteoric diagenesis
Thin section, plane polarized light. Scale bar = 1 mm
2 Sample 8
Biomicrosparite (floatstone)
Foraminifera are accessory components of the Cretaceous floatstones. They commonly exhi-
bit, as the one shown here, micritized tests. Note areas of clotted micrite that subsisted
recrystallization
Thin section, plane polarized light. Scale bar = 1 mm
3 Sample 2
Biomicrosparite (floatstone)
In spite of extensive recrystallization, blue-green algal laminae can be recognized. The
observed clotted structure may be in some way associated with these algae. On the left side,
a cross section of an echinoid spine showing incipient micritization and relicts of syntaxial
rim cement
Thin section, plane polarized light. Scale bar = 1 mm
4 Sample 11
Biomicrosparite (packstone)
Allochems consist mostly of echinoid fragments showing rim cement. The dark spheroidal
objects are bauxite ooids which were incorporated to the biogenic debris at deposition time
thus indicating ongoing bauxitization
Thin section, plane polarized light. Scale bar = 1 mm
5 Samle 10
Conglomeratic bauxite
Limestone fragments show features commonly found in caliche. The clast on the left is
laminated and exhibits circumgranular cracking. On the lower right, non-laminated glaebu-
les are cemented with microspar. A bauxit ooid (arrow) is also shown
Thin section, plane polarized light. Scale bar = 1 mm
Microfacies analysis of limestones from the Upper Cretaceous
383;
384 David Delvalle & Stanko Buser
Plate 2
1 Sample 19
Intrapelmicrite (wackestone to packstone) '
Detritic tiny tooth-like crystals are calcite pseudomorphs after gypsum. They are arran-
ged along straight lines indicating growth on an even surface, probably algal mats. Algal
laminations can be observed on the left. Abundant components are peloids. Intraclasts are
rounded and mostly darker than the matrix
Thin section, plane polarized light. Scale bar = 1 mm
2 Sample 21
Algal biolithite (bindstone)
Irregular fenestral fabrics are characteristic of this laminated limestone. Binded material
consist of micrite and abundant peloids
Thin section, plane polarized light. Scale bar = 1 mm
3 Sample 24
Biopelmicrite (wackestone)
Charophyta remains are not very well preserved. The occurrence of these green algae in the
Kozina limestones has been one of the criteria indicating lacustrine conditions. However,
these algae have been found in other environments (see section 7.2)
Thin section, plane polarized light. Scale bar = 1 mm
Microfacies analysis of limestones from the Upper Cretaceous
385!
386 David Delvalle & Stanko Buser
Plate 3
1 Sample 49
Caliche crust
"Flower spar" calcite cement. Elongate calcite crystals grow in a rosette-like fashion as
a result of continued precipitation in a void. Such features are particularly indicative of
calcareous crusts
Thin section, plane polarized light. Scale bar = 1 mm
2 Sample 60
Caliche crust (?)
Clotted micrite fabric resulted from the abundance of peloids which exhibit incipient
crumbly fracturing
Thin section, plane polarized light. Scale bar = 1 mm
3 Sample 50
Caliche crust
View of a caliche pisoid displaying circumgranular and intragranular cracking. Note detritic
Microcodium grains in the nucleus. Glaebules of various sizes can be observed. Cement
consists of microspar
Thin section, plane polarized light. Scale bar = 1 mm
Microfacies analysis of limestones from the Upper Cretaceous
387 :
388 David Delvalle & Stanko Buser
Plate 4
1 Sample 5
Biomicrite (wackestone)
The algae Thaumatoporella as well as miliolids and other small foraminifera are common
constituents of the Cretaceous rocks from profile 2. The micritic matrix is locally
recrystallized and shows scattered silt - sized crystals and peloids
Thin section, plane polarized light. Scale bar = 1 mm
2 Sample 2
Biomicrite (wackestone)
Various sections of locally abundant planctonic foraminifera (Pithonella ?). Other small
foraminifera with completely recrystallized test are also shown
Thin section, plane polarized light. Scale bar = 1 mm
3 Sample 2
Brecciation textures due to karst processes are common features of the Cretaceous limesto-
nes. Such textures can be also viewed in photomicrographs (microbreccia). Fissures are not
always cemented with sparry calcite but, as shown in the photo, with micritic to silt - sized
calcite. Note small foraminifera with utterly recrystallized tests on the right
Thin section, plane polarized light. Scale bar = 1 mm
Microfacies analysis of limestones from the Upper Cretaceous
389
390 David Delvalle & Stanko Buser
Plate 5
1 Sample 9
Intrapelmicrite (wackestone to packstone)
Sample from the "Kozina limestones showing clotted micrite and crumbly fracturing.
Intraclasts probably consist of reworked soil material. Coatings can be readily distinguis-
hed from the original material by their darker color. The gastropod shell on the left is
recrystallized but still recognizable due to the micritic envelope
Thin section, plane polarized light. Scale bar = 1 mm
2 Sample 18
Foraminiferal biomicrosparite (packstone)
Biogenic allochems consist of Miliolid and other benthonic foraminifera. Other constituents
are peloids. The former micritic matrix recrystallized to microspar. Sample from the Miliolid
limestones
Thin section, plane polarized light. Scale bar = 1 mm
3 Sample 20
Algal and foraminiferal biomicrite (wackestone)
View of a sample collected from the Alveolina-Nummulites limestones. Several foraminifera
(nummulitids, lepidocyclina, rotalids) as well as coralline algae can be recognized
Thin section, plane polarized light. Scale bar = 1 mm
Microfacies analysis of limestones from the Upper Cretaceous
391
392 David Delvalle & Stanko Buser
Plate 6
1 Sample 26
The primary rock type may be regarded as a biopelmicrite (wackestone to packstone). The
primary texture has been heavily altered by in situ formed Microcodium. Microcodium is
ultimately indicative of pedogenetic processes which could only take place over rather
long emergence periods
Thin section, plane polarized light. Scale bar = 1 mm
2 Sample 55
A petal-like Microcodium aggregate replaces a foraminifera with perforated test {Europertia ?).
Microcodium aggregates are often found corroding primary limestone components and oblitera-
ting primary textures
Thin section, plane polarized light. Scale bar = 1 mm
3 Sample 41
Biosparite (grainstone)
Sample from the Miliolid limestones containing fossils of typical marine environments
(fragments of corals and dasycladacean algae). The former aragonitic shells have been
dissolved and only micritic envelopes are left
Thin section, plane polarized light. Scale bar = 1 mm
4 Sample 67
Foraminiferal biomicrite (wackestone)
Characteristic view of an Alveolina limestone. Accessory components are remains of echino-
ids and coralline algae. The micritic matrix is partially recrystallized.
Thin section, plane polarized light. Scale bar = 1 mm
Microfacies analysis of limestones from the Upper Cretaceous
393
394 =
David Delvalle & Stanko Buser
Plate 7
1 Sample collected right at the con-
tact between Upper Cretaceous
and Paleocene limestones. Note
the sharpness of the contact and
the contrasting limestone colors.
The paleorelief resulted from dis-
solution processes during suba-
erial exposure (karst)
Scale bar = 1 cm
2 Brecciation textures are
commonly observed in the
Kozina limestones. Some of
these breccia may have for-
med as a result of mechani-
cal reworking of more or
less consolidated lime mud.
Others, however, resulted
from bioturbation (or pedo-
turbation) or from diagene-
tic processes during calichi-
fication
Scale bar = 1 cm