GeolCarp_Vol62_No5_447

www.geologicacarpathica.sk

GEOLOGICA CARPATHICA

, OCTOBER 2011, 62, 5, 447—461 doi: 10.2478/v10096-011-0032-9

Introduction

The  present  study  focuses  on  the  Badenian  Ostracoda  from
the surroundings of Pokupsko, north Croatia. The investigated
area is part of the Banovina region, central Croatia, bordered
by the rivers Sava, Una, and Kupa. During the Middle Mio-
cene,  the  investigated  area  of  Banovina  was  located  at  the
south-western margin of the North Croatian Basin (NCB fur-
ther on), which represented the south-western margin of the
Pannonian  Basin  system  and  the  Central  Paratethys  Sea
(Fig. 1).

The Central Paratethys extended from Bavaria to the Car-

pathian mountain chain (Steininger & Rögl 1979, 1984; Rögl
& Steininger 1983, 1984; Rögl 1998, 1999). It was part of an
intercontinental bioprovince that, began to evolve in the Oli-
gocene,  and  was  formed  due  to  collision  of  the  European
(Tisa-Moesia)  and  African  Plates  (Horváth  &  Royden  1981;
Kováč  et  al.  1998).  During  the  Miocene,  connections  of  the
Central Paratethys with the Mediterranean and the Indo-Pa-
cific  Ocean  were  repeatedly  established  and  interrupted
(Steininger et al. 1988; Rögl 1996). Such unstable connections
resulted in sea-level oscillations (Haq 1991), different deposi-
tional modes and paleoecological conditions, thus resulting in
the development of different ostracod faunas.

The formation of the NCB was associated with a passive

continental rifting. A syn-rift phase began during the Ottnan-
gian and lasted until the Middle Badenian. The post-rift
phase lasted from the Middle Badenian to the Pliocene
(Pavelić 2001).

In the Central Paratethys, a threefold subdivision of the

Badenian (16.3—12.7 Ma) is generally accepted (Papp et al.
1978; Harzhauser & Piller 2007). The Early Badenian
(Langhian) sea-level rise and trangression are related to the
global sea-level cycle TB 2.3 (Haq et al. 1988). In the NCB,

Badenian Ostracoda from the Pokupsko area

(Banovina, Croatia)

VALENTINA HAJEK-TADESSE

and BOŽO PRTOLJAN

Croatian Geological Survey, Department of Geology, Sachsova 2, HR-10000 Zagreb, Croatia; *valentina.tadesse@hgi-cgs.hr

(Manuscript received May 14, 2010; accepted in revised form April 14, 2011)

Abstract: In this paper we present the results of the investigations on the Badenian (Middle Miocene) ostracods from
the Pokupsko area. For the first time the presence of Badenian aged sediments in Croatia can be supported by the
occurrence of ostracod biozonal markers. Four Badenian ostracod zones are established: Lower Badenian Biozone NO7
Acanthocythereis hystrix—Bythocypris lucida, Middle Badenian Biozone NO8 Eocytheropteron inflatum—Olimfalunia
spinulosa, and the two Upper Badenian Biozones NO9 Neomonoceratina laskarevi—Miocyprideis sarmatica elongata
and NO10 Carinocythereis carinata—Phlyctenophora farkasi. On the basis of the generally accepted paleoecology of
selected genera, we identified the following ostracod faunas: shallow-water marine, shallow-water brackish-marine,
shallow-water reef, and deep-water marine. The paleontological and trace element analyses suggest that the Pokupsko
ostracod fauna lived in shallow (50 m deep), warm, and limpid waters, connected to a deeper sea and occasionally
exposed to freshwater inflows.

Key words: Miocene, Badenian, North Croatian Basin, Ostracoda, biostratigraphy, paleoecology, trace elements.

the Early Badenian deepening event resulted in deposition of
marls and gravelly calcarenites in the offshore areas (Pavelić
et al. 1998).

The second Badenian cycle corresponds to the global cycle

TB 2.4. (Haq et al. 1988). It was followed by a regression and
the lowstand Ser2 of Hardenbol et al. (1998). During the Late
Badenian, the transgression flooded even the tips of the ex-
posed blocks that had formed isolated islands during the Early
Badenian. Marine sedimentation was initiated by the deposi-
tion of gravels, which are overlain by coralline algal beds.

Fig. 1. Geographical setting of the Pannonian Basin system with
marked position of the investigated area.

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GEOLOGICA CARPATHICA, 2011, 62, 5, 447—461

Finally, the renewed flooding belongs to the Late Bade-

nian Langhian/Serravallian cycle TB 2.5 (sensu Haq et al.
1988). Further deepening in the area of the NCB resulted in
the deposition of marls.

Generally, the Early Badenian transgressions were con-

trolled  by  both,  tectonics  (induced  mainly  by  the  back-arc
basin  rifting)  and  eustacy,  followed  by  forced  regression.
The Late Badenian transgression and regression were domi-
nantly  controlled  by  sea-level  changes  within  the  Central
Paratethys realm (Pavelić et al. 1998; Bakrač et al. 2010).

The results presented in this paper are exclusively based

on paleontological and geochemical analyses of the ostracod
fauna. The richness and diversity of the ostracod fauna in the
investigated area is the consequence of important changes in
the Badenian Paratethys, which had a positive effect on ma-
rine  organisms.  The  enrichment  of  marine  fauna  was  the
consequence  of  open  seaways  between  the  Mediterranean
Sea/Indo-Pacific  and  the  Pannonian  basin  complex  during
the Badenian (Rögl 1998; Popov et al. 2004; Harzhauser &
Piller 2007).

In addition to identification of the ostracode fauna, this study

focuses  on  (1)  paleoenvironmental  reconstructions;  (2)  Bade-
nian  ostracod-based  biozonation,  recognized  for  the  first
time in Croatia after the Miocene Paratethys Biozonation of
Jiříček (1983) and Jiříček & Říha (1990); and (3), compari-
son  of  the  investigated  ostracod  fauna  with  coeval  faunas
from other parts of the Central Paratethys and Tethys.

In our analysis of the ostracod fauna, we included all the

available samples; some of them were recently recovered
from logged outcrops and cores, others were already pre-
served at the Croatian Geological Survey.

Geological settings

The available literature on the Miocene deposits of the inves-

tigated area of Banovina is relatively sparse. The first geological
map of the Glinsko Pokuplje area, along with a short discus-
sion, was published by Štúr (1863). Tietze (1871) investigated
the stratigraphy of the older deposits, whereas Šuklje (1914)
suggested the existence of Tortonian, Sarmatian, and freshwater
Pliocene Congeria beds in the environs of Pokupsko.

Takšić (unpublished 1951) described geological and mining

relationships in the environs of Abes, and reported on the shaft
in  Stipan.  Kochansky-Devide  &  Slišković  (1978)  concluded
that  the  deposits  of  Banovina  are  of  the  Middle  Miocene,
probably Late Helvetian (Karpatian) age. This conclusion is
based  on  determinations  of  the  Congeria  species  and  com-
parison with similar deposits on Mt Medvednica, as well as
on the fact that the freshwater deposits are overlain by Leitha
Limestone.

Jurišić Polšak (1979) determined the Lower Sarmatian

mollusc fauna of Glinsko Pokuplje. In an unpublished report
related to the geological map of the Vrginmost—Topusko—
Viduševac area, Šikić K. & Šikić L. (1960) described the
Dugo Selo and Stipan coal-bearing deposits.

Geological investigations associated with mapping of the

Karlovac sheet, Basic Geological Map of former Yugoslavia
1 : 100,000, were carried out from 1974 to 1976, and all the

field  and  laboratory  reports  are  stored  at  the  Croatian  Geo-
logical Survey. The micropaleontological report on the Cre-
taceous  and  Tertiary  samples  of  the  Karlovac  sheet  (Šikić
1974  unpubl.)  concluded  that  the  oldest  Neogene  deposits
are represented by freshwater sediments immediately under-
lying Tortonian deposits with poorly preserved ostracods of
reputed  Helvetian  age.  According  to  the  same  author,  the
marine  Tortonian  deposits  start  with  the  Spiroplectammina
carinata  (Spirorutilus  carinatus)  Biozone.  Later,  Pikija
(1984; unpubl. report) concluded that the Badenian deposits
transgressively  and  unconformably  overlie  the  older  depos-
its,  the  latter  ranging  from  the  Triassic  dolomites  to  basal
breccias, Paleogene clastites, tuffs and tuffites.

During the investigations on the thickness and spatial distri-

bution of subsurface coal-bearing deposits in the village of
Stipan, Vrginmost—Lasinja area (Lukšić 1985, unpubl.), Miknić
(1985, unpubl.) micropaleontologically analysed 16 cores and
confirmed the presence of Badenian strata for two of them.

Bajraktarević (1983) analysed foraminiferal fauna and

nannoplankton from Glinsko Pokupje (localities Čremušnica,
Babin potok, and Ilovačak) and had assigned the Badenian
age to the deposits (Spiroplectammina carinata Zone).

In a paper on the Neogene ostracod assemblages of Yugo-

slavia, Sokač & Krstić (1987) described the Šljivovac locality
as one with a rich and well-preserved freshwater ostracod fauna.
In her Master’s thesis, Hajek-Tadesse (unpublished, 2000)
described the ostracod fauna from Pokupsko.

Study sites and methods

Study sites

The investigated area is situated near the village of Pokupsko,

Banovina region, south of the Kupa River in Croatia (Fig. 2).

In addition to the Pokupsko outcrops, two cores at the Stipan

locality  (BS-3  and  BS-10)  and  ten  samples  acquired  during
the  1974  Basic  Geological  mapping,  Karlovac  sheet,  have
been  available  for  this  study.  We  have  also  analysed  five
previously  collected  samples  from  the  area;  these  samples
are  available  at  the  Department  of  Geology,  Croatian
Geological Survey.

Pokupsko

The bulk of the samples has been collected at the Pokups-

ko outcrop near the Kupa River, along the unpaved road run-
ning  parallel  to  the  Kupa  fluvial  terrace,  one  kilometer
southwest  from  Pokupsko.  The  outcrop  extends  15 m  in
width and it is 5 to 6 meters thick. It consists of yellowish,
poorly  cemented  sandstones,  alternating  laterally  with  yel-
lowish-white  sandy  marls.  The  outcrop  is  very  friable,  and
the bedding cannot be observed.

Stipan

The samples labelled Stipan well (BS), previously recov-

ered near the Stipan village between Vrginmost and Lasinja
were assigned to the Badenian age (Lukšić 1985, unpubl.).

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The BS-3/84 well is situated in the Minići village, in an

area  known  as  Ostrožin.  The  sediment  core  is  composed  of
sandy-limy  Badenian  deposits,  whose  thickness  reaches  up
to  96.0 m;  coal  intercalations  occur  near  the  bottom  of  the
core. Micropaleontological samples were collected from the
intervals  42.00—42.10 m  and  59.90—60.00 m.  In  the  first
42.00—42.10 m  interval,  the  Badenian  deposits  are  fine-
grained,  and  sandy-limy.  In  the  second  interval  (59.90—
60.00 m), the deposits are marly-sandy.

The BS-10/84 well is situated in a ditch 200 m south of the

Šljivovac village, and it penetrated through 93 meters of
Badenian deposits. The analysed samples were collected
from sandy fossiliferous marls (interval 66.00—66.10 m).

Based on Lukšić’s (1985, unpubl.) results it is obvious that

the Badenian deposits in the Stipan wells and the surround-
ing area are stratigraphically younger than the coal-bearing
series, and/or unconformably overlie the older bedrock com-
posed of Cretaceous flysh-like facies and the volcanogenic-
sedimentary complex.

The Lower Badenian deposits consist of decimeter-thick

interbedded  Leitha  Limestone,  calcareous  sandstones,  and
light-yellow  massive  Nullipore  Limestone,  composed  of
Lithothamnium  lumps.  The  upper  parts  of  the  Badenian  are
composed of marls with varying amounts of carbonate com-
ponent, so that transitions from marls to calcareous marls to
marly limestones can be observed. Marls are sandy and fos-
siliferous,  and  sporadically  they  contain  tuffitic  intercala-
tions.  The  most  remarkable  Badenian  lithologic  member  is
the  grey  to  light-yellow  bedded  to  massive  organogenous
Leitha  Limestone,  which  is  often  accompanied  by  lime-
stones  with  abundant  macrofossil  shells.  The  peaks  of  all
major  neighbouring  hills  are  composed  of  the  same  type  of
sediment,  because  the  underlying  sandy-marly  parts  are
more easily eroded.

Samples from mapping of the Karlovac Sheet

During the 1974 geological mapping of the Karlovac

sheet, sections Sjeničak and Čremušnica were sampled for
micropaleontological analyses. Ten samples were collected

and these have contributed to the completion of the sampling
net in the investigated area. According to the field-note data,
the  samples  have  been  collected  from  various  sediments.
Samples KA/13816, 13817, 13818 and 13821 were collected
from  sandy-clayey  sediments;  13822,  16630,  and  15533
were  collected  from  marly-sandy  and  sandy  sediments;
15271  was  collected  from  sandy  sediments;  and  13703  and
13671 from clays.

Samples from the micropaleontological collection

The five samples found in the micropaleontological col-

lection of the Department of Geology were found among the
stored Neogene material labelled Jabukovac, Šljivovac, Pet-
rinja, Trepča and Bučica. Since the above samples do not
have any additional marks, it was impossible to pinpoint pre-
cise locations as well as additional information on accompa-
nying fauna, sediment type, and the environment in which
they were found.

Methods

The collected field samples were disaggregated by soaking

in  a  hydrogen  peroxide  solution  for  24  hours,  followed  by
washing  through  sieves  (0.5;  0.25;  0.125;  0.063 mm)  and
drying. Some of the samples needed extra cleaning and these
were  re-soaked  in  hydrogen  peroxide  and  treated  ultrasoni-
cally  for  approximately  20  seconds.  A  hundred  grams  of
each dried residue were observed under a stereomicroscope.
Ostracods and other fossil remains (foraminifers and gastro-
pods) were hand-picked, counted and determined. Ostracods
were qualitatively, not selectively picked in order to preserve
the relative composition of the thanatocoenosis.

The stored material was subjected to an additional clean-

ing process in an ultrasound dish after additional cleaning
the material was picked again.

For the geochemical analyses of trace elements, the avail-

able amount of shells (about 50 mg) was weighed into 30 ml
glass test tubes for one-time use, and 3 mg of concentrated
HCl p.a. was added. The solutions were then analysed in the

Fig. 2.  Location  map:  study
area  with  marked  position  of
Pokupsko  outcrops  (

l); two

wells Stipan (BS-3 ); and sam-
pling points (KA13671 •).

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GEOLOGICA CARPATHICA, 2011, 62, 5, 447—461

Croatian  Geological  Survey  by  a  simultaneous  ICP  atomic
emission  spectroscope  Jobin-Yvon  JY-5OP.  Concentrations
of Mg, Ca, Mn, and Sr were determined; small sample and di-
lution prevented determination of other elements. The accu-
racy  of  the  analyses  was  checked  by  the  parallel  analysis  of
the  International  Geological  Standard  Soil  Samples  GXR-5,
GXR-6, and SJS-1, verified by USGS. The data were statisti-
cally analysed using the statistical package STATISTICA.

Photographs were made with the SEM at the Ina Naftaplin,

Zagreb. All ostracod specimens are stored in the repository
of the Croatian Geological Survey.

In this paper we essentially followed the ostracod classifi-

cation of Morkhoven (1963), Hartmann & Puri (1974) and
Horne et al. (2002).

Paleontological and geochemical analyses

Ostracods

The Badenian ostracod fauna from 17 localities (22 sam-

ples) analysed from the vicinity of Pokupsko is interesting due
to its diversity and richness (Table 1; Figs. 3, 4). We have de-
termined a total of 45 genera and 64 species. Samples were
grouped according to differences or similarities of the ostra-
cod fauna at one locality and by correlation between different
localities.

In addition to the presence of zonal markers for the Ostra-

cod Biozone for the Badenian (Jiříček 1983; Jiříček & Říha
1990), we attempted to define the attribution of samples to a
particular zone, out of the four Badenian ostracod zones rec-
ognized  so  far.  However,  the  ostracod  zonations  should  be
treated  with  caution,  because  some  new  results  in  ostracod
research  have  increased  the  stratigraphic  range  of  several
species (Zorn 2003, 2004; Gross 2006).

Pokupsko

The Pokupsko locality contains the majority of the species

determined in this paper. Due to poor bedding conditions, the
samples  in  the  field  were  not  taken  continuously.  Following
the  analysis  of  the  ostracod  fauna,  and  based  on  the  differ-
ences  observed  in  quantitative  and  qualitative  representation
of genera and species (differences in colour) and on sedimen-
tological  determinations,  the  eleven  samples  were  classified
into two groups, labelled Pokupsko I and Pokupsko II.

In Pokupsko I group, the representatives of the tribe Aurli-

nae are the most abundant, especially the species Aurila angu-
lata, A. cicatricosa, A. haueri, A. punctata, Senesia trigonella,
S. cinctella, Pokornyella deformis; also abundant are the fol-
lowing  species:  Tenedocythere  sulcatopunctata,  Pachycau-
dites  ungeri,  Heliocythere  vejhonensis,  Costa  edwardsi,  C.
reticulata,  C.  punctatissima,  Carinocythereis  carinata,
Occultocythereis bituberculata, Grinioneis haindigeri, Henry-
howella  asperrima,  Pterygocythereis  calcarata,  Olimfalunia
plicatula, O. spinulosa, Olimfalunia sp. and Cytheridea sp.

Less abundant are the following species: Cytherella com-

pressa, Bairdoppilata sp., Callistocythere aff. canaliculata,
Echinocythereis scabra, Cnestocythere lamellicostata, Loxo-

corniculum hastatum, L. punctatella, Neomonoceratina sp.
and Xestoleberis cf. X. glabrescens.

The Pokupsko II group contains all of the above mentioned

species  from  Pokupsko I,  and  in  addition  it  contains  an  in-
creasing  number  of  deeper  water  species:  Krithe  sp.,  Para-
krithe  dactylomorpha  and  Eucythere  sp.  The  genus
Semicytherura  is  also  abundantly  represented,  with  Semi-
cytherura alata, S. acuticostata, S. cf. S. alifera, Semicytheru-
ra  sp.  as  well  as  Eucytherura  textilis,  Hemicytherura  sp.,
Cytheretta tenuipunctata dentata, Flexus triebeli and a few re-
mains  of  Ruggieria    cf.  R.  micheliniana,  species  which  oc-
curred only in the Pokupsko II group.

Also, in contrast to the Pokupsko I group, ostracods in the

Pokupsko II group are preserved mostly in adult stage and
with closed valves. The age of both groups, Pokupsko I and
Pokupsko II, is Late Badenian.

The Stipan wells

Two cores have been studied: BS-3 with two intervals and

BS-10 with one interval.

BS-3 (42.00—42.10 m). The most abundant species within

this  interval  are  Olimfalunia  plicatula,  Olimfalunia  sp.,
Cytheridea sp. and C. acuminata; less abundant are Cytherella
compressa, Aurila angulata, Senesia cinctella, Callistocythere
aff.  canaliculata  and  Cnestocythere  lamellicostata,  whereas
Costa  edwardsi,  Loxocorniculum  hastatum  and  Bosquetina
dentata are present with only a few specimens. Of particular
significance is the recovery of Cytherelloidea sissinghi, which
represents its first finding within the Paratethys realm.

BS-3 (59.90—60.00 m). This interval contains a rich and di-

verse  ostracod  fauna.  Of  particular  interest  is  the  finding  of
Ruggieria ex gr. carinata and Cytherelloidea sissinghi, forms
that are not frequent in Paratethys. Their findings in the inves-
tigated  area  represents  an  additional  proof  of  transgressive
events  in  the  Badenian  and  migration  of  ostracods  from  the
Tethys to Paratethys. Also, abundant are the representatives of
the  family  Cyprididae,  indicative  of  deeper  water  environ-
ment,  such  as  Paracypris  polita  and  Phlyctenophora  affinis,
as well as Henryhowella asperrima and Pterygocythereis cal-
carata. Similarly to the preceeding interval of the same well,
the  species  Olimfalunia  plicatula,  O.  spinulosa,  Olimfalunia
sp.,  Cytheridea  sp.,  Cytherella  compressa  are  also  abundant,
whereas the folloving are less numerous:  Callistocythere  aff.
canaliculata,  Costa  edwardsi,  Loxocorniculum  hastatum,  L.
punctatella, Xestoleberis  cf. X. glabrescens, Bosquetina den-
tata and Bythocythere cf. B. neerlandica.

The sample from this interval differs in its faunal content

from the upper interval of the same well, being more similar
to the fauna from the well BS-10 (60.00—60.10 m).

BS-10 (60.00—60.10 m). The ostracod assemblage from

this sample is one of the most interesting in the whole area
investigated. It is dominated by valves of adult individuals,
80 % of which are very well preserved.

The finding of the key species Acanthocythereis hystrix is

important for the age determination, and it supports an earlier
attribution  to  the  older  part  of  the  Badenian  (unpublished
Miknić  1985).  In  addition  to  that  species,  the  sample  con-
tains  important  representatives  of  the  family  Cyprididae,  as

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well  as  Ruggieria  ex  gr.  carinata,  Cytherella  inaequalis,
Cytherelloidea sissinghi, Henryhowella asperrima, Pterygo-
cythereis  calcarata,  Bythocythere  cf.  B.  neerlandica,  Olim-
falunia  plicatula,  Cytheridea  sp.,  Flexus  triebeli,  Costa
edwardsi and Xestoleberis cf. X. glabrescens.

According to the results obtained from the three intervals

in two cores, we argue that the rich and well preserved ostra-
cod fauna from the Stipan cores is interesting for several rea-
sons.  In  the  BS-3  well,  a  continuous  transition  from  the
upper part of the Lower Badenian into the lower part of the
Middle  Badenian  may  be  discerned  based  on  foraminifers
(unpublished  Miknić  1985),  and  a  comparison  of  ostracod
fauna  from  the  well  BS-3  59.90—60.00 m  interval  with  the
BS-10 60.00—60.10 m interval can be carried out.

The recovery of the biostratigraphic marker-species Acan-

thocythereis hystrix in the sample BS-10 (60.00—60.10 m) is
extremely important, as it proves the Early Badenian age of
the  sample.  The  occurrence  of  typical  representatives  of  a
deeper water environment, such as: Acanthocythereis hystrix,
Henryhowella asperrima, Bythocythere cf. B. neerlandica and
Paracypris polita suggests deepening of the basin; Cytherel-
loidea  sissinghi  and  Ruggieria  ex  gr.  carinata,  which  have
previously not been recorded from the Badenian deposits of
the Central Paratethys, indicate migration of ostracod faunas
from the Tethys into this region. The data about the reverse
migration of the ostracod fauna, namely from the Paratethys
to  Tethys  (Szczechura  &  Abd-Elshafy  1988)  also  support
these considerations.

Samples collected during mapping of the Karlovac sheet

Ten samples collected during the geological mapping of

the Karlovac sheet are classified into six groups according to
the similarity of the ostracod fauna observed.

Karlovac I (KA 16630, 15533). This group is distinguished

from  the  other  groups  by  the  presence  of  the  index  species
Acanthocythereis  hystrix,  indicating  the  Early  Badenian  age.
Other  abundant  species  include  Ruggieria  ex  gr.  carinata,
Pterygocythereis  calcarata,  Henryhowella  asperrima,  Flexus
triebeli, Cytheridea sp., and less numerous Grinioneis haidin-
geri, Aurila haueri, Costa edwardsi and Bairdoppilata sp.

Karlovac II (KA 13703). The recovery of Eocytheropteron

inflatum in sample KA 13703 has been decisive in separating
this  sample  into  a  different  group.  In  addition  to  Eo-
cytheropteron inflatum, this group is characterized by a mixed
shallow-water/deep-water  ostracod  fauna.  The  abundant  os-
tracod  fauna  includes  Ruggieria  ex  gr.  carinata,  Phlycteno-
phora  affinis,  Paracypris  polita,  Olimfalunia  spinulosa,
Olimfalunia  sp.,  Cytheridea  sp.,  Pontocythere  cf.  P.  curvata
and,  less  numerous,  Aurila  cicatricosa,  Bosquetina  dentata
and Senesia sp.

Karlovac III (KA 13817, KA 13816). In the third group,

the most numerous species are shallow-water representatives
of  the  genus  Aurila,  with  A.  angulata,  A.  cicatricosa,  A.
haueri, A. punctata, Senesia trigonella, S. cinctella, as well
as the species Costa edwardsi, C. reticulata, Cytheridea sp.,
Pontocythere cf. P. curvata, Callistocythere aff. canalicula-
ta,  Cnestocythere  lamellicostata,  Phlyctenophora  affinis,
Grinioneis  haidingeri,  Pterygocythereis  calcarata,  Olim-

falunia plicatula, O. spinulosa and Olimfalunia sp. Similar
to the above-mentioned groups, this group also contains
Ruggieria ex gr. carinata, and the age of the sample is deter-
mined as Middle Badenian; this age was also documented by
foraminifers (unpublished Šikić L. 1974).

Karlovac IV (KA 13818, KA 13821). The fourth group has

been  based  on  findings  of  Miocyprideis  sp.  in  two  samples.
The dominant species are Cytheridea sp., Costa edwardsi and
C.  reticulata,  but  Olimfalunia  plicatula,  Carinocythereis
carinata,  Senesia  cinctella  and  A.  cicatricosa  are  also
present,  though  less  numerous.  Specimens  of  the  genera
Costa and Olimfalunia show environmentally cued polymor-
phous changes (Peypouquet et al. 1988) on their valves. The
Late Badenian age of the sample has been determined based
on the ostracod fauna. According to the foraminiferal assem-
blage,  the  “Upper  Tortonian”  Ammonia  beccarii  Zone  was
determined (unpublished Šikić L. 1974).

Karlovac V (KA 15271). The dominant species in this

group  are  Cytherella  compressa,  Cytherella  inaequalis,
Paranesidea sp., Phlyctenophora affinis and Aurila angulata.
Contrary to previous groups, this group is impoverished with
respect  to  both  the  number  of  species  and  the  number  of
specimens. On the basis of the ostracod fauna and foramini-
fers  (unpublished  Šikić  L.  1974),  the  Late  Badenian  age  of
that sample has been determined.

Karlovac VI (KA 13822, KA 13671). This group has been

identified based on the shallow-water fauna, which, in con-
trast to the KA III group, is not dominated by the genus Aurila.
This group is characterized by Phlyctenophora affinis, Costa
edwardsi,  C.  reticulata,  Cytheridea  sp.,  C.  acuminata  and
less  abundant  deeper  water  species  Paracypris  polita,
Bosquetina  dentata,  Echinocythereis  scabra  and  Pterygo-
cythereis calcarata. The age of the sample is Late Badenian.

The ostracod fauna in the samples collected during mapping

yields  some  important  information  on  Badenian  deposits  in
the  investigated  area.  The  key  species  Acanthocythereis  hys-
trix  in  the  first  group  and  Eocytheropteron  inflatum  in  the
third group define the age of these deposits as Early and Mid-
dle  Badenian.  The  common  characteristic  of  the  first  three
groups  is  the  presence  of  the  “new-entry”  species  Ruggieria
ex gr. carinata, whereas the presence of the genus Miocypri-
deis  in  the  fourth  group  indicates  global  paleoecological
changes  in  the  Paratethys  realm  during  the  transition  from
Middle to Late Badenian.

Šljivovac

Although the Šljivovac locality is situated close to Stipan,

its  faunal  content  is  more  similar  to  the  ostracod  fauna  from
the B-3 well (59.90—60.00 m interval), except for the species
Parakrithe dactylomorpha, Pontocythere cf. P. curvata, Para-
cytheridea sp. and Cytherella beyrichi, which were found only
in  that  sample.  In  the  Šljivovac  sample,  the  most  abundant
species  are  Henryhowella  asperrima,  Pterygocythereis  cal-
carata, Cytheridea sp., Costa edwardsi, Olimfalunia plicatula
and Callistocythere aff. canaliculata. Of particular importance
is findings of the “new-entry” species Cytherelloidea  sissinghi,
which  prior  to  this  study  has  not  been  identified  in  the
Paratethys  realm.  The  environmentally  cued  polymorphous

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ppm

Mg/Ca Sr/Ca

Aurila

9214

1497

0.033

0.0055

Cytherella

5942

1650

0.019

0.0052

Bairdoppilata

5327 163 1170 0.012 0.0026

Cytheridea

3868 108 1512 0.012 0.0045

Tenedocythere

2935

983

0.014

0.0063

Table 2: Obtained results of trace element analyses for selected
ostracod genera from the Pokupsko area.

changes (Peypouquet et al. 1988) have been observed on
valve surfaces of Costa and Olimfalunia. The Middle Baden-
ian age of this sample has been determined on the basis of the
ostracod fauna and Sokač’s observations (pers. comm.).

Trepča and Bučica

The faunas from the two samples are very similar. They

are  both  dominated  by  Callistocythere  aff.  canaliculata,
Cnestocythere lamellicosta, Aurila angulata, A. haueri, Costa
edwardsi,  Olimfalunia  plicatula  and  O.  spinulosa.  In  addi-
tion to the species mentioned in the Trepča sample, less nu-
merous are Senesia sp. and Bosquetina dentata, absent in the
Bučica sample, which contains, instead,  Cytheridea sp. Ac-
cording to the analysis of the ostracod fauna and comparison
with fauna from other localities, the Late Badenian age has
been determined.

Jabukovac and Petrinja

The main characteristic of the two localities is the predom-

inance of adult specimens of Pontocythere cf. P. curvata.
Other species common to both localities include Xestoleberis
cf. X. glabrescens and Olimfalunia plicatula. In addition, the
Jabukovac locality contains Cytherella compressa, C.
inaequalis and Paracypris polita.

The Petrinja sample contains a richer fauna than the above

described.  In  addition  to  the  above  species  it  also  includes
Bairdoppilata  sp.,  Phlyctenophora  affinis,  Callistocythere
aff.  canaliculata,  Aurila  angulata,  Pokornyella  deformis,
Tenedocythere sulcatopunctata, Costa edwardsi, Grinioneis
haidingeri,  Olimfalunia  plicatula  and  Cytheridea  acuminata.
The  Late  Badenian  age  of  this  sample  has  been  determined
on the basis of the ostracod fauna.

Trace element analyses of the Upper Badenian ostracod
valves

Ostracods are organisms sensitive to environmental

changes  that  control  their  occurrence,  distribution,  and  re-
production  (Barbieri  et  al.  1999;  Holmes  &  Chivas  2002).
Ostracod valves are made of Ca and Mg-carbonates, but other
chemical  elements,  including  Sr,  K,  Na,  Mn,  Fe,  and  Ba,
may also be present.

Chivas et al. (1983) were among the first who showed that

certain geochemical parameters of ostracod valves yielded more
detailed  infomation  on  the  environment  in  which  the  fauna
lived. The analysis of concentrations and ratios of Ca, Mg, Sr,
and  Mn  in  ostracod  valves  from  the  vicinity  of  Pokupsko  (all
samples  studied  come  from  the  sixth  biofacies,  thus  being
Late  Badenian  in  age)  enabled  us  to  do  the  paleoenviron-
mental  reconstruction.  Generically  determined  valves  were
separated for geochemical analyses. According to Barbieri et
al. (1999), this is acceptable since species of the same genus,
or even phylogenetically related genera, have similar Sr and
Mg concentrations.

The selected genera inhabited both shallow-water (Aurila,

Cytheridea, Tenedocythere) and deep-water environments
(Cytherella, Bairdoppilata).

The concentrations of elements vary in different deposits,

depending on regional features, differences in mineralogy, and
ratio between inorganic and organic components. Chivas et
al. (1983) argued that the amount of Mg in ostracod valves
depends on the temperature and concentration of Mg

in wa-

ter, whereas the Sr content depends directly on the concentra-
tion of Sr

in water. In sea water, the concentration of Mg and

Sr increases with the increasing salinity and decreases with the
decreasing temperature, whereas the higher Mn concentrations
are  due  to  increased  influx  of  terrigenous  material  (Prasada
1996). The ratio of Sr/Ca and Mg/Ca concentrations in ostra-
cod  valves  remains  unchanged  if  the  water,  temperature  and
salinity  remain  constant.  If  the  value  of  Mg/Ca  ratio  varies,
and  the  Sr/Ca  ratio  remains  constant,  the  water  temperature
varies  and  salinity  is  constant.  Finally,  if  both  the  Sr/Ca  and
Mg/Ca  ratios  vary,  changes  in  salinity  and  insignificant
changes in water temperature are expected.

Dweyer et al. (1995) were among the first to postulate a

connection between the variations in Mg/Ca ratio in valves
of the deep-water genus Krithe and the water depth in which
the genus lived. The authors concluded that the lower Mg/Ca
values in valves correspond to lower water-temperature, and
higher values correspond to higher temperatures.

In both organic and inorganic aragonite, the Sr/Ca ratio of-

ten increases with the lowered temperature (Prasada 1996),
whereas the rather stable Sr/Ca values are indicative of an
equalized temperature.

Certain conclusions can be drawn from the above men-

tioned data and the results obtained by geochemical analyses
shown in Table 2 and Fig. 5a—c.

The greatest deviations from the group of analysed genera

in the first two diagrams (Fig. 5a,b) is found in the genus
Bairdoppilata. The low Mg/Ca and Sr/Ca ratios, as well as the
increased concentrations of Mn (163 ppm), distinguish this
genus from the group of other genera. This may be explained
through the interpretation of different micro-environments.

It is known, that the genus Bairdoppilata inhabits both

very  shallow  and  deep  marine  environments.  According  to
the  geochemical  analyses  of  the  Pokupsko  sample,  we  sug-
gest  a  shallow-water  environment  with  considerable  influx
of terrigenous material, and so close to lower salinity  fresh-
water sources enriched in Mn as indicated by the lower val-
ues of the Mg/Ca and Sr/Ca ratios.

As shown in Fig. 5b,c, the genus Bairdoppilata is joined

by the genus Tenedocythere, in its deviation from the group
of shallow-water marine forms. The lowest Sr concentrations
(985 ppm) in the valves of this genus, as well as the low Mg
concentration, indicate the change in water salinity. Because
we are dealing with a marine environment, such deviations

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Fig. 5. a – Mg/Ca versus Sr/Ca plot in the valves of analysed gen-
era. b – Sr/Ca versus Mn concentration plot in the valves of analy-
sed genera. c – Sr concentration versus Mn concentration plot in
the valves of analysed genera.

may be explained by decreased magnesium and strontium
values as a consequence of crystal growth (Prasada 1996).

The other three analysed genera do not show considerable

deviations regarding the concentrations of elements, the ex-
ception being genus Cytherella, in which the lowest Mn con-
centration  (46 ppm)  and  the  highest  Sr  concentration
(1650 ppm) have been determined. The deviations in Mn and
Sr concentrations may be explained in two ways, either as an
adaptability  to  greater  depths,  or  life  in  a  protected  marine
shallow-water environment, devoid of freshwater influx. The
decision,  on  which  hypothesis  should  be  accepted  can  be
reached only after analysis of the whole ostracod assemblage
in which Cytherella has been found.

Taking into consideration all the above-mentioned data, the

environment during life of the selected genera corresponded to
the model of an open/half-closed lagoon with periodical fresh-
water influx, presented in the paleoenvironment reconstruc-
tion section of this paper.

Discussion

Correlation of samples based on analysed fauna

The studied ostracod faunas were collected in a relatively

small investigated area on the basis of common characteris-
tics, namely key species, facies indicative species and com-
mon biocoenoses. Accordingly, we were able to classify 25
samples into 14 groups; groups were classified into six bio-
facies. These biofacies do not necessarily represent biostrati-
graphic units; sometimes, they are identified exclusively
according to the paleoecological diversity of the constituent
fauna (Fig. 6.).

First biofacies. It includes the Stipan BS-10 (60.00—60.10 m)

fauna, and its temporal and faunistic equivalent, KA I (15533,
16630); these two groups share three important characteristics.

Both groups contain the key species Acanthocythereis hys-

trix,  which  determines  the  attribution  of  the  samples  to  the
homonym  biozone  of  the  Lower  Badenian  Biozone  (NO7)
Acanthocythereis  hystrix—Bythocypris  lucida  (Jiříček  1983;
Jiříček & Říha 1990).

Also, both groups contain a mixed deeper and shallow-wa-

ter fauna. Among the deeper water forms, the most abundant
are  Henryhowella  asperrima,  Pterygocythereis  calcarata
and  Bythocythere  neerlandica,  whereas  the  shallower  envi-
ronment  is  characterized  by  four  genera,  namely  Olimfalu-
nia, Cytheridea, Flexus and Costa.

The findings of the so-called “new-entry” species Rug-

gieria  ex  gr.  carinata  and  Cytherelloidea  sissinghi  imply,
the  transgressive  changes  occurring  during  the  Early  Bade-
nian,  and  the  migration  of  ostracod  species  from  southern
parts  of  the  Mediterranean,  indicating  the  establishment  of
the Tethys—Paratethys connection.

The second biofacies continuously succeeds the first biofa-

cies.  It  includes  samples  from  the  Stipan  BS-3  well  (59.60—
60.00  m)  and  the  Šljivovac  locality.  Like  the  first  facies
described above, it contains a mixed fauna of deeper water os-
tracods  such  as  Henryhowella  asperrima,  Pterygocythereis
calcarata, Bosquetina sp., Paracypris polita, Phlyctenophora
affinis  and  Bythocythere  neerlandica  and  shallow-water
forms,  dominated  by  genus  Olimfalunia  with  several  species
of the Olimfalunia—Cytheridea—Callistocythere—Costa associ-
ation. Due to the abundance of genus Olimfalunia and contin-
uous  sedimentation  that  is  clearly  observed  in  the  Stipan
well  samples,  it  is  possible  to  assign  the  samples  from  this
biofacies  to  the  Middle  Badenian  ostracod  Biozone  (NO8),
Eocytheropteron  inflatum—Olimfalunia  spinulosa  (Jiříček
1983; Jiříček & Říha 1990).

Both samples contain the species Ruggieria ex gr. carinata

and Cytherelloidea sissinghi.

The third biofacies continuously overlies the second biofa-

cies. The samples of this biofacies BS-3 (42.00—42.10 m) and

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Fig. 6. Ostracod biozonation of the Badenian samples from the Pokupsko area.

KA (13817, 13816) are distinguished from the previous facies
on  the  basis  of  paleoecological  differences.  The  biofacies  is
characterized  by  shallow-water  ostracod  assemblages,  that
dominate  over  the  less  numerous  deeper  water  forms.  The
most abundant form is genus Olimfalunia (with three species),
associated with genera  Aurila, Costa and Cytheridea. On the
basis of the predominance of the Olimfalunia genus, this bio-
facies  is  assigned  to  the  Middle  Badenian  ostracod  Biozone
(NO8)  Eocytheropteron  inflatum—Falunia  spinulosa  (Jiříček
1983; Jiříček & Říha 1990).

The two samples of this biofacies differ in two details. In

sample BS-3 we found the species Cytherelloidea sissinghi,
which  is  missing  in  the  KA II  group,  whereas  in  KA II  we
found Ruggieria  ex gr. carinata, which is not present in the
BS-3  sample.  In  this  level  we  notice  the  last  occurrence  of
the new-entry species Cytherelloidea sissinghi.

Fourth biofacies. Samples from the KA III group

(13703). The recovery of well preserved and numerous adult

specimens  of  Eocytheropteron  inflatum
(which is found only in this sample) is impor-
tant  biostratigraphical  information.  It  is  well
known  as  the  key  species  of  the  Middle
Badenian  Biozone  in  the  Paratethys  (Jiříček
1983; Jiříček & Říha 1990) and therefore its
recovery in the fourth biofacies indicates the
Middle Badenian, Biozone (NO8) Eocythero-
pteron  inflatum—Olimfalunia  spinulosa.  This
biofacies is characterized by mixed deep-wa-
ter  and  shallow-water  ostracod  assemblages,
with  Phlyctenophora  affinis,  Paracypris
polita,  Olimfalunia  spinulosa,  Cytheridea
sp.,  Pontocythere  cf.  P.  curvata,  and,  less
numerous, Aurila cicatricosa, Bosquetina sp.
and  Senesia  sp.  We  also  noticed  the  last
occurrence  of  Ruggieria  ex  gr.  carinata  in
this level.

Fifth biofacies. The samples from the

KA IV group (13818, 13821) are classified as
a separate biofacies. The most significant fea-
ture of this facies is the presence of Miocypri-
deis sp. Though it is not the marker species of
the  well  known  Upper  Badenian  Zone  Mio-
cyprideis elongata (Jiříček 1983), the recovery
of this genus nevertheless indicates paleoeco-
logical changes, such as decreasing water sa-
linity  and  depth,  which  are  characteristic  of
the region during the lowest part of the Upper
Badenian,  namely  the  Miocyprideis  elongata
(NO9) Biozone (Jiříček 1983; Jiříček & Říha
1990).

The samples are dominated by the shallow-

water  genera  Cytheridea  and  Costa;  less
abundant  are  Olimfalunia  plicatula,  Carino-
cythereis  carinata,  Senesia  cinctella  and
Aurila  cicatricosa.  Environmentally  cued
polymorphous  changes  (Peypouquet  et  al.
1988) on valves of the Olimfalunia and Costa
genera have also been noticed.

Sixth biofacies. This biofacies includes

samples  from  the  Upper  Badenian  groups  of  Pokupsko I,
Pokupsko II,  Trepča,  Bučica,  Jabukovac,  Petrinja,  KA V
(13822, 13671), and KA VI (15271). This is the richest biofa-
cies,  according  to  both  the  number  of  analysed  samples  and
the number of determined species.

The differences in ostracod faunas within the analysed sam-

ples are most clearly visible in the distribution of deep-water
species  and  different  shallow-water  assemblages.  Thus,  the
Pokupsko II  group  contains  more  abundant,  typically  deep-
water  species,  Henryhowella  asperrima,  Pterygocythereis
calcarata, Krithe sp., Parakrithe dactylomorpha and Echino-
cythereis scabra, whereas in the Pokupsko I group we found
only  three  deep-water  species,  Henryhowella  asperrima,
Pterygocythereis calcarata and Echinocythereis scabra.

The recovery of Echinocythereis scabra is particularly in-

teresting, because in addition to Pokupsko, it has been iden-
tified only in the KA V sample, and is generally rarely found
in the Paratethys. That species is most frequently found in

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GEOLOGICA CARPATHICA, 2011, 62, 5, 447—461

the contemporaneous deposits of the Aquitanian Basin,
France (Moyes 1965; Ducasse & Cahuzac 1997).

Each of the above-mentioned samples or groups also contains

a  recognizable  dominant  shallow-water  ostracod  association.
Thus,  Pokupsko I  is  characterized  by  the  Aurila—Tene-
docythere—Costa  association,  and  Pokupsko II  by  the  Semi-
cytherura—Cytheridea—Cytheretta association.

In the Karlovac IV group, the dominant genera are Cyther-

ella,  Paranesidea,  Aurila,  and  in  Karlovac V,  Costa  and
Cytheridea.  The  Jabukovac  and  Petrinja  samples  are  charac-
terized by the shallow-water Pontocythere—Costa—Cytheridea
assemblage,  whereas  Trepča  and  Bučica  contain  the  Aurila—
Costa—Olimfalunia association.

The entire ostracod assemblage – except some species – is

well  known  from  the  Badenian  deposits  of  Central  Para-
tethys. It is most similar to the Badenian fauna of the Vienna
Basin, Lower Austria (unpublished Huber-Mahdi 1984; Zorn
2003, 2004; Gross 2006; Gebhardt et al. 2009). The shallow-
water part of the fauna correlates well with the shallow-water
Badenian fauna of  Podvin, Vienna Basin, southern Moravia
(Zelenka  1985),  and  the  deeper  water  fauna  of  Pokupsko
shows  similarities  with  the  Middle  Miocene  deeper  water
fauna  of the pre-Karpatian depression of Poland (Szczechu-
ra  1994).  The  described  fauna  is  also  comparable  with  the
Badenian fauna from six wells in southwest Poland (Paruch-
Kulczycka 1992).

A non-isolated realm for the studied samples is further

suggested  on  the  basis  of  similarities  with  the  Middle  Mio-
cene  ostracod  assemblages  of  a  wider  geographical  area.
Thus, we may distinguish a dozen species that are common
within  the  Middle  Miocene  ostracod  fauna  of  Libya  and
Egypt (Szczechura & Abd-Elshafy 1988), the island of Crete
(Sissingh  1972),  the  Langhian  ostracods  from  Sicily
(Dall’Antonia  et  al.  2001),  Northern  Sardinia  (Bossio  et  al.
2006), the Rhodanian Basin (Carbonnel 1969), the Miocene
fauna  of  the  NW  Basin  of  northern  Germany  (Uffenorde
1981)  and  the  Middle  Miocene  ostracods  from  the  West
Coast of India (Bhandari et al. 2001).

Ostracod paleoecology of the surroundings of Pokupsko

The regional Middle Miocene geological events are closely

associated with the ostracod fauna distribution. The open-
ings or closings of sea straits, transgressions, regressions, as
well as climatic changes, had a deep impact on composition
of the ostracod association, preservation state of the valves,
frequency of particular genera and species, and the occur-
rence of polymorphous changes on ostracod valves.

Differences in the state of preservation and composition of

biocoenoses are probably the result of different energy con-
ditions and sedimentation rates (Whatley 1983; Boomer et
al. 2003).

Slow sedimentation typically results in well preserved,

separated valves, and complete biocoenoses are found. The
Lower and Middle Badenian samples analysed in this paper
are an example of such a rate of sedimentation.

During high-energy conditions and/or rapid sedimenta-

tion, unfavourable conditions for preservation occurred, re-
sulting in selectively sorted valves. Complete, selectively

sorted carapaces (usually lacking juvenile specimens), with
non-separated valves, are found mostly in Upper Badenian
samples of the Pokupsko surroundings.

The lack of autoecological data on Badenian species im-

pedes  the  paleoecological  reconstruction.  However,  general
assumptions  on  living  conditions  of  the  representative  gen-
era may partly compensate for the absence of data and yield
reliable  conclusions.  Thus,  in  this  paper,  indicative  genera
were selected, and their occurrence may be associated with a
particular type of environmental conditions.

In the ostracod fauna of the surroundings of Pokupsko,

heavily calcified genera with strongly ornamented valve sur-
faces  are  dominant,  indicating  shallow  marine  habitats.
These  include  Aurila,  Senesia,  Tenedocythere,  Callisto-
cythere,  Costa,  Grinioneis,  Hemicytherura,  Cytheridea,
Xestoleberis, Semicytherura and Olimfalunia.

Within this shallow-water fauna, two specific groups of

genera may be distinguished. The species within the first
group are limited to tropical and subtropical seas, and most
frequently suggest reefal areas. These include Paranesidea,
Loxoconcha and Cytherelloidea. The second group is distin-
guished by the Miocyprideis genus, indicating a brackish en-
vironment.

The transitional, shallow-water/deep-water group is identi-

fied by the following genera: Pterygocythereis, Echino-
cythereis, Bosquetina, Cytherella and Ruggieria.

A separate group is represented by the deep-water genera

Krithe, Parakrithe, Eocytheropteron, Henryhowella, Argil-
loecia, Acanthocythereis, Paracypris and Bythocythere,
whose recent representatives live at a depth of about 100 m.

On the basis of the different genera identified, the ostracod

fauna from the surroundings of Pokupsko can be defined as a
shallow-water  marine  fauna,  a  shallow-water  brackish-ma-
rine  fauna,  a  shallow-water  reef  marine  fauna,  and  a  deep-
water  marine  fauna.  Note  that  the  majority  of  samples
contain predominantly mixed fauna.

The dependence of ostracods on environmental conditions

can be very helpful in the paleoenvironment reconstruction.
The analysis of the entire fauna suggests that the ostracod
fauna of the Pokupsko surroundings lived in a shallow ma-
rine environment, down to 50 m depth, and had a connection
with the open sea. The water was warm, as indicated by find-
ings of several warm-water new-entry species, as well as by
an abundance of the foraminifer Borelis (the Pokupsko sam-
ple), which prefers very warm water and implies tropical to
subtropical water temperatures. The species is also found in
a similar ostracod assemblage from the Middle Miocene de-
posits of North Africa (Szczechura & Abd-Elshafy 1988).

The majority of ostracods are robustly built, indicating

high-water energy and well-oxygenated water conditions,
except for the Šljivovac sample that contains pyritized
valves. The pyritized valves in a sample of the Middle Bade-
nian age agree well with the conclusions of Šútovská (1990),
who, in the Middle Badenian of the Carpathians, assumes the
occurrence of an anoxic facies although; stratification is not
fully developed due to shallow-water depths.

Salinity of the water was similar to the salinity of the

present-day seas. In closed lagoons it was higher, and in
near-shore areas lower due to freshwater influxes.

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GEOLOGICA CARPATHICA, 2011, 62, 5, 447—461

Lithologies of the analysed samples (clay, sandy clay,

marly sand, and sand) reinforce the conclusions obtained by
the microfauna analyses and suggest a tripartite division of
the marine environment into a near-shore zone, transitional
zone and shelf.

The near-shore zone limits the estuaries and semi-open la-

goonal  environments  shorewards.  The  near-shore  environ-
ment is wave-influenced, especially during storms. Locally,
it  is  also  influenced  by  tides,  wind-driven  currents,  and
freshwater  influx.  This  type  of  environment  is  moderately
stable,  characterized  by  moderately  high-energy,  with  sand,
silt and clay as typical sediment types.

The transitional zone is made up of commonly alternating

fine-grained sand, silt, and clay, and is characterized by
maximum development of both the species and individuals.
The environments more distal from the shore are beyond the
river-induced freshwater influence and wave motion, except
during storms. This is a stable, low energy environment.

The ostracod fauna of the shelf environment varies from

poor to rich; the sediment is clayey, partly sandy or silty.

Each of the above zones, striking parallel to the shore, has

its own “inhabitants” that may be grouped into ecozones that
coincide with the above mentioned depth distribution of os-
tracods.

Given all the available data, the paleoenvironment of the

Pokupsko ostracods was probably shallow marine and often
turbulent and periodically connected to the open sea and
freshwater influx.

Conclusion

A very rich and diverse fauna of ostracods has been identi-

fied within the Badenian layers at seventeen locations
around Pokupsko.

The ostracods belong to the suborders of Platycopa and

Podocopa,  and  their  families  of  Cytherellidae,  Bairdiidae,
Cyprididae, and Cytheridae. Forty-four genera and sixty-six
ostracod  species  have  been  identified  altogether.  The  entire
ostracod  fauna  has  locally  been  classified  into  six  biofacies
based on similarities/differences between different faunas.

The Lower Badenian Zone NO7 Acanthocythereis hystrix—

Bythocypris lucida, encompasses the samples of the first bio-
facies  and  was  identified  based  on  findings  of  the  index
species  Acanthocythereis  hystrix,  “new-entry”  species  Rug-
gieria ex gr. carinata, and Cytherelloidea sissinghi, and nu-
merous  deep-water  ostracods.  According  to  the  faunal
composition  and  comparison  with  the  same  biozone  recog-
nized  in  other  areas  of  the  Paratethys,  it  is  presumed  that
samples  from  Pokupsko  belong  to  the  youngest  part  of  the
NO7 Zone.

The second Biozone NO8 (Middle Badenian) Eocytheropte-

ron  inflatum—Olimfalunia  spinulosa,  continuously  overlies  the
previous  zone.  The  samples  of  the  second,  third,  and  fourth
biofacies were included in this biozone. This is based on identi-
fication  of  the  index  species  Eocytheropteron  inflatum  in  the
fourth  biofacies,  the  numerous  species  of  Olimfalunia  in  the
second and third biofacies, as well as the different composition
of ostracod communities in the three biofacies.

The third Biozone NO9 Paijenborchella (E.) laskarevi—

Miocyprideis sarmatica elongate marks the beginning of the
Late Badenian in the Central Paratethys. The samples of the
fifth biofacies belong to this zone; they are also character-
ized by the occurrences of Miocyprideis sp.

The fourth ostracod Biozone NO10 Carinocythereis cari-

nata—Phlyctenophora  farkasi,  marks  the  latest  Late  Bade-
nian  in  the  Central  Paratethys.  The  samples  of  the  sixth
biofacies are assigned to this zone and are the most abundant
in this area. There are certain indications that two subzones
can  be  distinguished  within  this  zone  in  the  wider  area  in
Croatia.

As in some other areas, changes in the ostracod distribu-

tion closely follow regional geological events. Transgressive
phases resulted in very diversified faunas, while regressive
phases resulted in a great number of specimens and species.

Diversified ostracod fauna is the main feature of the Lower

Badenian and Middle Badenian samples. The discovery of
“new-entry” species from the Tethys, Cytherelloidea sissinghi
and Ruggieria ex gr. carinata, both of which were not fre-
quent in the Paratethys, shows free connections between the
Tethys and Paratethys areas.

Sea-level drop and the disconnection between the Tethys

and  Paratethys  caused  paleobiogeographic  ‘disintegration’.
According to the isotopic studies of Badenian foraminifers oc-
curring  below  evaporates  in  the  Carpathian  Foredeep  basin
Peryt D. & Peryt T. (2010) suggest that the interrupted com-
munication  of  the  Paratethys  with  the  ocean  was  a  conse-
quence  of  eustatic  sea-level  fall,  possibly  related  to  climatic
cooling, and it was coupled with a tectonic closure of the con-
nection  with  the  Tethys.  The  deep-water  ostracods  became
less  abundant  and  shallow  brackish-marine  fauna  became
dominant in all paleogeographic domains. Sea-level drop and
the probable isolation of the area in the south-western margin
of the North Croatian Basin resulted in the Badenian freshwa-
ter sediments and coal-bearing horizons (Bakrač et al. 2010).

A regressive trend, which continued in the later Badenian,

resulted in the recovery of numerous shallow-water species.
However, the presence of deep-water species in the Upper
Badenien samples implies oscillations of water level, as well
as occasional penetration of deep-water ostracod fauna in re-
sponse to renewed flooding in the Late Badenian (sensu Haq
et al. 1988).

The analyses of Ca, Mg, Sr and Mn were carried on cara-

paces of the selected Late Badenian genera, including Aurila,
Cytherella, Cytheridea, Bairdoppilata and Tenedocythere.
The results obtained contributed to the reconstruction of the
paleo-environment.

Acknowledgments: The authors wish to thank professors Ana
Sokač,  Ivan  Gušić  and  Zlatan  Bajraktarević  for  their  helpful
and fruitful suggestions. Particular thanks to Slobodan Miko,
for performing the analysis of trace elements. The authors are
very grateful to Ivo Suša from the Croatian Geological Survey
for  technical  support,  and  to  Renata  Slavković  and  Zdenka
Barbić  from  INA,  Zagreb,  for  preparing  SEM  microphoto-
graphs. The present investigation is  part of the research that
was supported by the Department of Geology, Croatian Geo-
logical  Survey,  and  the  Ministry  of  Science,  Education  and

460

HAJEK-TADESSE and PRTOLJAN

GEOLOGICA CARPATHICA

GEOLOGICA CARPATHICA, 2011, 62, 5, 447—461

Sports  Project  Grant  No. 181-1811096-1093:  “Basic  Geo-
logical  Map  of  the  Republic  of  Croatia  1 : 50,000”.  For  im-
provement  of  the  English  text  we  warmly  thank  to  Ivan
Gušić  and  Antun  Husinec.  We  are  grateful  to  Elsa  Gliozzi
and Irene Zorn for their valuable and helpful reviews.

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