1. INTRODUCTION

Due to their lithological and sedimentological char-

acteristics, the geometry and genesis of sedimentary

bodies of biocalcarenite with large-scale cross-bedding

attract special attention in studies of the Neogene sedi-

ments on the hill-sides of the Slavonian Mts. They are

characterised by a variety of cross-bedding sets in

respect to the thickness and angle of inclined beds, type

of cross-bedding within certain sets and dimensions of

the sets, as well as to their lateral and vertical relations

with or without prominent erosion and redeposition. In

spite of the fact that such Neogene sediments are wide-

ly distributed along the Croatian SW margins of the

Pannonian basin, not much data has been published.

Shoreline Cross-bedded Biocalcarenites (Middle Miocene)

in the Podvrπko-©njegaviÊ Area, Mt. Psunj, and their Petroleum

Significance (Poæega Subdepression - Eastern Croatia)

Josipa VELI∆ , Josip TI©LJAR , Ivan DRAGI»EVI∆ and Ivan BLA©KOVI∆

This is especially true for the interpretation of the depo-

sitional systems in which these biocalcarenitic sedi-

ments were formed. Apart from a short review of the

contemporary understanding of such sediments, this

paper deals with the structure and interpretation of the

cross-bedded biocalcarenites in the Podvrπko- ©njegaviÊ

area on the SE slope of Mt. Psunj (Fig. 1) and with their

significance (potential) as petroleum and gas reservoir

rocks.

In the last 25 years, the Poæega subdepression and

its marginal parts have been explored on several occa-

sions. Gravimetric and geoelectrical measurements as

explained in the work of KOVA»EVI∆ & MUJAGI∆

(1975) led to a number of conclusions - the depression

has a markedly blocky structure; the maximal thickness

of Neogene and Quaternary sediments is at least 2500

m; there is a predominance of fine-grained clastics and

faults were determined along the northern and western

margin of the valley.

In a later paper (MILJU© & VUGRINEC, 1997)

faults at roughly the same positions are shown in maps

and cross-sections. A prognosis for the thickness of the

transgressive Miocene sediments was given for the first

time. For example, 5 kilometres in the direction of the

valley from the basement outcrops on its western mar-

gin (the location of the Podvrπko -©njegaviÊ cross-bed-

ded biocalcarenite sedimentary bodies), the transgres-

sive Miocene sediments reach a thickness of 1000 m.

Results of a more comprehensive study of the Poæe-

ga subdepression were published by NAJDENOVSKI

& UDJBINAC (1980). Their set of subsurface maps

depict the strike of faults and their throws at various

marker horizon levels, the position of a number of anti-

clines and synclines, as well as the thickness of specific

sediment intervals. The Poæega subdepression was de-

termined by NAJDENOVSKI (1988) to be a typical

intramontane basin, t e c t o n o g e n e t i c m i c r o t e c t o n o c o n -

c e n t r e with certain sedimentary phases marked by

inverse movements - the western part subsided faster

during deposition of the Miocene sediments, and the

eastern part subsided more in the Pliocene. 

In the OkuËani-Pakrac-Novska area on the western

slopes of Mt. Psunj, seven lithofacies were determined

within a continuous zone of Badenian sediments (BLA-

G EOL.  C ROA T. 53/2 281 - 293 6 Figs. ZAGREB 2000

Key words: Cross-bedded biocalcarenites, Shoreline

deposits, Subaqueous dune, Petroleum and gas re-

servoir sandstone, Synsedimentary tectonics, Bade-

nian, Poæega subdepression, Pannonian basin, East-

ern Croatia.

University of Zagreb, Faculty of Mining, Geology and Petroleum

Engineering, Pierottijeva 6, HR-10000 Zagreb, Croatia.

Abstract
The extensively distributed bioclastic sedimentary bodies in the

Podvrπko-©njegaviÊ Area, Mt. Psunj (Poæega Subdepression, Eastern

Croatia) are mostly composed of fragments of bryozoans, echinoids,

lamellibranchs and corallinaceans. Apart from this, a relatively com-

positionally uniform, but granulometrically variable bioclastic detri-

tus occurs, which also contains a smaller proportion (5-30%) of silici-

clastic grains of medium to coarse sand, as well as sporadic pebbles

up to 60 mm in diameter. These sediments are characterised by

remarkably large-scale cross-bedding with erosional surfaces clearly

delimiting the sets. They are interpreted as shallow-marine shoreface

subaqueous dunes, sand bars and barriers formed on the nearshore -

mainly shoreface area during the Late Badenian in a high-energy

depositional cycle with strong synsedimentary tectonics. 

With regard to the petroleum-geological reservoir characteristics,

the described Middle Miocene cross-bedded biocalcarenites are com-

pared with numerous large oil and gas pools globally, and in other

localities in Croatia on the margins of inselberg massifs between the

Drava and Sava rivers and south of the Sava river.



282 Geologia Croatica 53/2

©KOVI∆ et al., 1982). They range from coarse-grained

near-shore and the biohermal and biocalcarenite fore-

reef and back-reef sediments, through slope facies to

turbidites. Large masses of horizontal and cross-bedded

biocalcarenites with 5-40% of siliciclastic grains were

described. They were interpreted in terms of bioclastic

sands that originated from decomposition of biolithite

reefs, and were transported and deposited during cyclic

variations in water energy, predominantly waves and

tide currents. Hydrodynamics controlled the intensity of

reef destruction, as well as the transport, sorting and

accumulation of detritus in shallow high-energy envi-

ronments. 

Based on outcrop analysis in the vicinity of the Pod-

vrπko village, the cross-bedded bioclastic Badenian sed-

iments on the SE slopes of Mt. Psunj, close to the mar-

gin of Poæega subdepression, were interpreted as sub-

marine fan-delta deposits (BLA©KOVI∆ et al., 1985).

The authors had postulated the basic principles of for-

mation of such a delta and assumed (later found to be

correct) that kind of large cross-bedded sedimentary

body and other similar ones surely exist at other places

on the rim of the Poæega subdepression. Similar conclu-

sions were reached during the survey for the Basic geo-

logical map. JAMI»I∆ et al. (1987) explained that the

Badenian sediments in the Gornji Vrhovci area are

developed in a delta facies. The studied, nearly 100-m-

thick section of conglomerates consists of several tens

of cross-bedded sets that are 0.5 to 3 metres thick. The

conglomerates are composed of well-rounded pebbles

Fig. 1  Location map and geological setting (JAMI»I∆, 1989; JAMI»I∆ & BRKI∆, 1987).



of different metamorphic and igneous rocks, as well as

of lithothamnium, lamellibranch and echinoid frag-

ments. The Badenian sediments in the broader sur-

roundings of Podvrπko were also found to be of deltaic

origin (JAMI»I∆ et al., 1989). Within almost a hundred

metres of the conglomerate sequence, a number of

cross-bedded sets were discerned. 

Lower Miocene freshwater clastics that were depo-

sited before the Badenian cross-bedded biocalcarenites

were studied by PAVELI∆ (1998) at Mt. Poæeπka gora,

not far from the Podvrπko locality. He interpreted these

freshwater sediments, probably of Ottnangian age, to

have been formed in two successive sedimentary-tec-

tonic phases - an older alluvial and a younger lacustrine

phase. 

The uninterrupted Ottnangian-Badenian sequence of

sediments along the southern margin of the Pannonian

basin system was described by PAVELI∆ et al. (1998)

in terms of a depositional sequence that can be divided

into three parts. The lower part is composed of laminat-

ed lacustrine siltstones with sandstone interbeds and of

horizontally bedded offshore-shoreface sandstones that

contain bioclasts of shallow-marine organisms. The

middle and upper part of the sequence is characterised

by trough cross-bedded sandstones interlayered with

thin-bedded horizontally laminated biocalcarenites

(mostly composed of the fragments of corallinaceans,

bryozoans, lamellibranchs and echinoids) and by trough

cross-bedded conglomerates with erosional contacts

between the sets. The authors interpreted these sedi-

ments as having been formed by migration of sub-

aquatic 3D-dunes in the upper shoreface environment.

The planar cross-bedded sandstones and conglomerates

with inclination of sets in the 20-30° range and dipping

towards the sea compose the middle part of the succes-

sion. They are interpreted in terms of the small-scale

foresets of the Gilbert-type marine fan-deltas. The top

part of the succession is composed of massive marls

with biocalcarenite interbeds. These marls are interpret-

ed as the offshore sediments, and biocalcarenites as tur-

bidites - Ta - b intervals of the Bouma sequences. In light

of the above knowledge on the Badenian biocalcaren-

ites our aim was to give more details on their genesis,

synsedimentary tectonic influence and petroleum geolo-

gy significance, bearing in mind the distribution of such

deposits and their global importance as reservoir rocks.

2. LITHOLOGIC COMPOSITION, STRUCTURE

AND GEOMETRY OF THE SEDIMENTARY

BODIES

In the Podvrπko-©njegaviÊ area (Fig. 1) the Mioce-

ne (mostly Badenian) sediments unconformably and

transgressively overlie the crystalline rocks of Mt.

Psunj. The sediments are mostly periclinally positioned

and as a rule covered by younger deposits. 

The cross-bedded biocalcarenite sedimentary bodies

in the Podvrπko - ©njegaviÊ area have a monotonous

lithological composition: sandy biocalcarenites prevail

over biocalcirudites. Apart from the more or less uni-

form, but granulometrically very variable bioclastic

detritus, they contain a minor amount (5-30%) of silici-

clastic particles which have dimensions of medium- to

coarse-grained sand, and sporadically pebbles up to 60

mm in size. Fragments of reef and fore-reef organisms

are most frequently found. There is a marked predomi-

nance of more or less rounded and abraded, poorly to

well sorted bioclasts of bryozoans, echinoids, ostreids

and of corallinacean algae (lithothamnions), and frag-

ments of corals and benthic foraminifers are less abun-

dant. 

Siliciclastic grains and pebbles, mostly of the size of

coarse and medium-grained sand (0.2-1.5 mm) and

partly gravel-sized (2-60 mm), are mainly composed of

the monocrystalline and polycrystalline quartz grains,

and fragments of crystalline rocks, feldspars and micas.

Together with quartz grains, the quartzite fragments

and mica-schists prevail over the granitoid, gneiss and

phyllite fragments. Feldspars are represented by the

exceptionally fresh grains of microcline and sodium

plagioclases, and micas by the coarse leaves of mus-

covite and a small fraction of comparatively fresh

biotite. The siliciclastic grains are generally poorly

rounded, although semi-rounded and rounded grains

and pebbles occasionally appear. 

Within certain more lithified sets of cross-bedding,

matrix is practically absent and the biocalcarenites are

characterised by the grain-support of the bioclasts and

siliciclastic grains. The intergranular, intraskeletal and

interskeletal pores are filled with a relatively large

quantity (in comparison with the total rock volume) of

macrocrystalline drusy mosaic calcite cement, and all

the echinoid bioclasts are covered by the variously

thick layer of syntaxial calcite cement. In these kinds of

biocalcarenites, where the detritus is very much washed

out, the more prominent or total lithification of the sets

of cross-bedding is caused by the three factors: the

absence of the micrite and clayey matrix, high level of

sorting and comparatively high proportion of the syn-

taxial and drusy mosaic calcite cement. Lithified sets of

cross-bedding stand out between the majority of the

sets, or parts of sets in most of the sets of cross-bed-

ding, that are poorly lithified or unlithified (Figs. 2, 4

and 5). So, there was some primary reason for the

development of the cyclically changing character of the

clast fabric, i.e. composition of the coarse-grained fore-

sets and fine-grained bottomsets (Fig. 4).

Apart from the poorly sorted bioclasts and variable

ratio of siliciclastic grains, the upper parts of the sets of

large-scale trough cross-bedding of the biocalcarenites

contain a large proportion of fine bioclastic detritus

(silt-sized) with a very small amount of finely dispersed

clayey matrix. This composition hindered lithification,

especially cementation, of this type of biocalcarenite

making them very poorly lithified and subjected to ero-

sion (Figs. 2, 3 and 4). It is common when grain avalan-

che is the main transport mechanism on foresets that

grain size increases downward.

283VeliÊ, Tiπljar, DragiËeviÊ & BlaπkoviÊ: Shoreline Cross-bedded Biocalcarenites (Middle Miocene)...



284 Geologia Croatica 53/2

Among the most prominent characteristics of these

sediments, and the most important one from the sedi-

mentological point of view, is the well-observable

cross-bedding (Figs. 2, 3, 4 and 5) with erosional sur-

faces that clearly delimit certain sets of the large-scale

trough cross-bedding (Figs. 3, 4 and 5). The sets of

cross-bedding are between 60 cm and 3 m thick and

have a width in the range of 1.5-15 m (Figs. 3, 4 and 5).

The sets are thinning upwards.

The succession of foresets within one set of cross-

bedding is characterised by a regular repetition of gran-

ulometric composition and of the ratio of fossil and sili-

ciclastic material. The foresets of the cross-bedding

have the greatest thickness in cross-sections oriented

parallel to direction of transport, where thickness in the

5-30 cm range can be measured and the angle of dip

maximally reaches 25-35° in sections perpendicular to

transport. Following the reduction of thickness, the

angle of foresets is reduced until it finally becomes par-

allel to the position of the bottomsets, if bottomsets are

developed (Fig. 4). The coarse-grained foresets (biocal-

carenite - biocalcirudite) indicate tangential or sig-

moidal foresets deposited by grain avalanche, and fine-

grained bottomsets (Fig. 4) turbulence deposition of

fine grains from cloud instead of grain avalanche. Poor

cementation of fine-grained bottomset sediment (Fig. 4)

is due to the granulometric composition of bottomsets

(rich in carbonate silt and pelite).

The upper margins of the sets of large-scale cross-

bedding are usually sharply cut and have the character

of an eroded surface (Figs. 2, 3 and 4). A number of co-

lateral sets are cut by the same erosional surface and

Fig. 2  Sets of cross-beds of vari-

able lithification due to varia-

tions in grain size and in sort-

ing of the same biocalcarenite

beds. In the middle part of the

photo there is a low-angle

cross-bedded unit (X) with ra-

pid erosion of the large-scale

cross-bedded biocalcarenites.

Podvrπko, Mt. Psunj.

Fig. 3  Detail from Fig. 2: erosional

surface at the top of a large-

scale cross-bedding biocalcare-

nite and a low-angle cross-bed-

ded unit (X).



285VeliÊ, Tiπljar, DragiËeviÊ & BlaπkoviÊ: Shoreline Cross-bedded Biocalcarenites (Middle Miocene)...

covered by a 10-70 cm thick layer of low-angle (mostly

3-10°) cross-bedded biocalcarenite (X on the Figs. 2

and 3). They are mostly composed of well-sorted bio-

clasts with 10-15% siliciclastic grains. In the upper part

they contain no matrix and are strongly cemented by

large quantities of syntaxial rim calcite cement and

drusy mosaic calcite cement. This layer has the shape

and sedimentological characteristics which used to indi-

cate a high-energy and relatively shallow water envi-

ronment: at about the level of breaking waves (“outer

planar facies” - ELLIOT, 1986) or may be in the swash

zone. Thin layers with low-angle cross-bedding often

occur between large-scale cross-bedded foresets in the

upper part of biocalcarenite bodies (Fig. 2). 

As deduced from the general direction of dip of the

layers with low-angle cross-bedding, the dip of the

foresets of some troughs that were transected roughly

parallel to direction of transport, the generalised direc-

tion of palaeotransport was to the SE. This was sea-

wards from the Mt. Psunj crystalline massif that was

land in Miocene times. 

Such a general direction of progradation of the

cross-bedded sediments is paralleled by the reduction of

the dip angle of inclined layers, and by reduction of the

thickness of inclined layers within the sets. It is also

noted that certain cross bedded layers that cover ero-

sional surfaces of a number of sets, thin in the same

direction, and that there is a general change in the gran-

ulometric composition of the biocalcarenites. In the

proximal parts of sets, the foresets are composed of the

more coarse-grained, strongly cemented and clast-sup-

ported biocalcarenite that is rich in fossil fragments.

Fig. 4  Typical weathering morphol-

ogy of the cross-bedded biocal-

carenites with lithified coarse-

grained foresets and unlithified

fine-grained bottomsets - Pod-

vrπko, Mt. Psunj.

Fig. 5  Parts of two sets of the large-

scale cross-bedded biocalcaren-

ites with erosional surface and

low-angle cross-bedded biocal-

carenite unit (in the centre of

figure).



286 Geologia Croatica 53/2

The distal, mildly inclined layers are composed of the

more fine-grained, matrix-rich and matrix-supported,

poorly cemented sandy biocalcarenite. With increasing

distance from the source area, there is a general

increase in the ratio of the fine-grained detritus and

matrix in respect to the coarser fossil detritus. Finally,

the seaward ends of the sedimentary bodies are com-

posed of the clayey-carbonate (marly) detritus, already

mixed with the basin sediments. 

Generally, in the direction of dip of the foresets -

i.e. in direction of transport, with increasing distance

from the source area sea-wards, the following charac-

teristic changes are observed: a gradual thinning of the

sets and of the foresets, general reduction of the dip

angle of the foresets within the sets, the cross-bedding

becoming markedly less observable together with lower

visibility of the contacts between the sets. 

2.1. CRYSTALLINE BASEMENT AND

SEDIMENTS BENEATH THE CROSS-BEDDED

BIOCALCARENITE SEDIMENTARY BODIES

The Neogene sedimentary complex of the Poæega

subdepression that transgressively (unconformably)

overlies the crystalline basement (in petroleum-geologi-

cal papers treated as the basement rocks) is illustrated

in the schematic outline of sedimentation during the

Badenian age (Fig. 6). Comparison of this schematic

outline with the geological setting given in Fig. 1, facil-

itates an explanation for the character of the biocal-

carenite basement. In the study area, the basement of

the cross-bedded biocalcarenite bodies is mostly com-

posed of clayey-silty-marly sediments that have the

characteristics of fine clastic material deposited in a

low-energy environment. There are no coarser frag-

ments of crystalline rocks, which is interpreted as a qui-

et transgression in the Karpathian and Early Badenian.

In spite of the fact that corrallinacean-bryozoan

biolithite build-ups were not preserved in situ w i t h i n

both discussed study areas, the existence of numerous

and widely distributed build-ups of this kind and of the

fore-reef shoals (ecologically suitable for development

of the thick-shelled lamellibranchs, echinoids and

corals), is deduced from large quantities of their bio-

clasts. 

The fine-grained silty-clayey clastics, rich in pelagic

foraminifera, that are laterally equivalent to the bioclas-

tic sedimentary bodies and are biostratigraphically

determined as the Lower Badenian, were deposited in

the deeper, undisturbed and clean, definitely marine

environment. The following species are the most com-

mon: Globigerinoides trilobus ( R E U S S ) , G l o b i g e r i n a

concinna R E U S S , Praeorbulina glomerosa B L O W ,

Orbulina suturalis BRÖNNIMANN and Orbulina bilo -

bata d’ORBIGNY. 

Such relatively thin sediments (100-150 m in the

Golobrdac area - Fig. 1) not only underlie the facies

described above, but are also present in a more exten-

sive area on the south-eastern slopes of Mt. Psunj

where they have a variable thickness and comprise the

basal member of other Badenian lithofacies. The con-

tact between the silty-clayey basal part and the coarse

sandy bioclastic facies is transitional, but over very

short time-span (considering its thickness) and compris-

es a general upward-coarsening sequence. 

2.2. LATERAL EQUIVALENTS OF THE

CROSS-BEDDED BIOCALCARENITE

SEDIMENTARY BODIES

Laterally to the cross-bedded biocalcarenite sedi-

mentary bodies, the silty-clayey basal part of Badenian

rocks is regionally overlain by several lithofacies char-

acterised by the significant increase of a sandy compo-

nent. This can either be bioclastic limestone detritus

originating from the reefal material that was accumulat-

ed in the thicker biocalcarenite layers, or the succession

of sand-clay-marl carbonate sequences that have some

turbidite characteristics and are dominated by siliciclas-

tic material. 

As a rule, the cross-bedded biocalcarenite bodies in

the studied areas pass laterally into the biocalcarenites

with less marked bedding, or into massive biocalcaren-

ites. This contact is transitional and poorly identifiable

in the field due to the lack of outcrops. As a result of

the periodicity of sedimentation, in the more distal part

of depositional area, the prograding cross-bedded sedi-

mentary bodies that are the most distant from the clastic

source area, are characterised by a transitional contact

between the underlying cross-bedded foreshore-sho-

reface biocalcarenite bars, barriers, or deltaic lithofacies

and the turbidites. This is, for instance, the case

between the Badenian sediments and Sarmatian and

Lower Pannonian deposits on the western slopes of Mt.

Psunj in the OkuËani-Pakrac-Novska area (BLA©KO-

VI∆ et al., 1982). Another example is within the mas-

sive marls with biocalcarenite interbeds - Ta - b i n t e r v a l s

of Bouma-sequences on the southern slope of Mt.

Papuk (PAVELI∆ et al., 1998). 

2.3. SEDIMENTARY COVER OF THE

CROSS-BEDDED BIOCALCARENITE BODIES

In spite of the fact that the locations with the best

exposures of the cross-bedded biocalcarenite sedimen-

tary bodies do not enable the analysis of the entire ver-

tical lithofacies succession (there are no outcrops of

overlying sediments), a number of conclusions can be

drawn from the data acquired in the more general area.

Sets of cross-bedding are gradually reduced in thick-

ness, the dip angle of the foresets is reduced and the

grains become smaller. All this, together with the less

pronounced textural characteristics and domination of

organic carbonate material over the siliciclastic in the

apical parts, points to the weaker transport of material

from the source area by increase in relative source dis-

tance and thus to the diminishing strength of the princi-

pal driving force of the periodic sedimentary transport.



287VeliÊ, Tiπljar, DragiËeviÊ & BlaπkoviÊ: Shoreline Cross-bedded Biocalcarenites (Middle Miocene)...

The Badenian limestone bryozoan reefs containing var-

ious proportions of the corallinaceans, fore-reef lamelli-

branchs and echinoids take over the role of the main

sedimentary source. 

Continuous sedimentation resulted in the cross-bed-

ded biocalcarenite sedimentary bodies being covered by

the mostly massive biocalcarenites without clearly

observable stratification. 

3. DEPOSITIONAL MODEL OF THE

CROSS-BEDDED BIOCALCARENITE

SEDIMENTARY BODIES

The exceptionally large and sporadically well expo-

sed outcrops of the cross-bedded biocalcarenite sedi-

mentary bodies (Figs. 2-5), compared with other data

sources that will be discussed, enable a generalised

interpretation of the depositional system to be made.

The principal elements of this depositional system are

defined by the lithological and sedimentological char-

acteristics of these bodies, by their geographic setting in

respect to the masses of Mt. Psunj and Mt. Papuk, as

well as by the Miocene geological evolution of the area.

The composition of the siliciclastic component, espe-

cially of the rock fragments, unaltered feldspars and

biotite, combined with other data define the sedimenta-

ry source areas and the low grade of sedimentary matu-

rity, i.e. that these sediments pertain to the first deposi-

tional cycle (of weathering, transport and deposition

during the Badenian age). The source material for the

sediments in Podvrπko area was derived from the crys-

talline rocks of Mt. Psunj (Fig. 1). A large proportion of

the organic limestone detritus (mostly of reefal bry-

ozoans but also of corallinaceans and of fore-reef echi-

noid origin) points to the existence of significant bio-

hermal build-ups and shallow-marine limestone sedi-

ments on the margins of the relatively shallow near-

shore zone of the Badenian marine area (Fig. 6). It is

impossible to asses how much of the detritus was deri-

ved from the Lower Miocene sediments, although JA-

MI»I∆ et al. (1989) mention the Lower Miocene clas-

tics close to the peak of Mt. Psunj which may also be

the potential source of detritus. 

The majority of Badenian biohermal and organic

shallow-marine limestone rocks were formed during the

phase of transgression (Fig. 6) - worldwide uplift of the

sea level (Late Karpatian to the Mid Badenian relative

sea-level rise - HAQ et al., 1987). The maximal redepo-

sition of organic detritus and progradation of bioclastics

in high-energy conditions containing various propor-

tions of siliciclastic material derived from the crys-

talline rocks happened during the relative sea-level fall

(Late Badenian). Apart from the eustatic changes, con-

temporaneous tectonic pulses cannot be ignored. Synse-

dimentary tectonics are characterised by the intermit-

tent reactivation of the marginal faults - uplift of the

crystalline massifs and relative subsidence of the near-

shore and central parts of the sedimentary area (Fig. 6).

Tectonic movements on the marginal faults are referred

to by KOVA»EVI∆ & MUJAGI∆ (1975), NAJDENO-

VSKI & UDJBINAC (1980), JAMI»I∆ (1983, 1989),

NAJDENOVSKI (1988) and PRELOGOVI∆ et al.

(1995, 1998).

The dynamics of depositional model are analysed in

several phases. The preliminary phase serves to

explain deposition of the underlying silty-marly sedi-

ments in the environment characterised by the similar

bathymetric conditions. In conditions of relative tecton-

ic quiescence, without significant uplift of the Mt. Psu-

nj crystalline rock masses, but with minor relative rises

of the sea-level, there is a reduction in the transport of

terrigenous material in the shallow and wide nearshore

zone of the sedimentary area. The mechanical and che-

mical weathering of the crystalline rocks takes place

but without significant transport towards the area of

deposition. There is also a lack of pronounced develop-

ment of limestone reefs on the rims of the nearshore

zone. Hydrodynamic factors influence deposition of the

silty-marly material in a wider and deeper basin area

without rock fragments or coarser particles in spite of

the relatively close source area. 

The preparatory depositional phase reflects the

influence of certain regional changes that happened.

These are: the rejuvenation of tectonic movements on

the marginal faults (KOVA»EVI∆ & MUJAGI∆, 1975;

JAMI»I∆, 1983, 1989; NAJDENOVSKI & UDJBI-

NAC, 1980; NAJDENOVSKI, 1988; PRELOGOVI∆ et

al., 1995, 1998), uplift of the land massifs and a general

trend of the relative rise of sea-level in the basinal part,

and relative sea-level fall at the nearshore (Fig. 6), and

also changes in climatic conditions. The tectonic reacti-

vation - uplift of the crystalline masses and a general

relative rise of the sea level resulted in the faster

mechanical weathering of the crystalline rocks and in

the stronger influx of terrigenous material in a wide and

morphologically variable coastal zone. The growth and

development of bioherms on the reliefed rims of the

shallow nearshore zone was favoured by the climatic

conditions and a general trend of sea-level rise. In this

way the back-reef platform became a shallow concave

sedimentary area. The sea-level rise was compensated

by the rate of deposition conditioned by the increased

influx of detritus and tectonic uplift. In some places this

balance resulted in preservation of the same bathymet-

ric conditions. In the high energy nearshore marine

environment, where relative sea-level fall occurred,

there was strong destruction of reefs and the organic

debris becomes further reworked and mixed with the

siliciclastic material brought from the land by torrents

and fluvial streams. The intrabasinal transport in the

basinal part (Fig. 6) is reduced in this phase - only a

small mass of the siliciclastic-bioclastic material that

accumulates is distributed in the wider basinal area

where it conformably overlies the previously deposited

silty-marly sediments. 

The first phase of deposition of the cross-bedded

biocalcarenite sedimentary bodies reflects a relatively

short-lasting process triggered by the reactivated tec-



288 Geologia Croatica 53/2

tonic pulses due to the uplift of land massifs, and by the

change in inclination of the dish-like back-reef plat-

form. This caused the sudden transport and redeposition

of large masses of bioclastic detritus and their mixing

with the siliciclastic material on foreshore - shoreface

environments. A sudden accumulation of the large

masses of detritus occurs in the foresets of cross-bed-

ded bodies - sand bars, barriers, 3D subaqueous dunes

and ebb-deltas, partly with the characteristic sigmoidal

shape of inclined layers. The fast progradation and

grain avalanche or grain fall transport of bioclastic

detritus is thereby presumed both for the bioclastic

material from the pronounced reefs, fore-reefs and fore-

reef shoals, and also for the siliciclastic detritus from

the land. Ebb-deltas are formed between the large sand

bars or barriers. Concurrently, apart from the bioclastic

shore-barrier sand bars and subaqueous dunes, the tur-

bidites were deposited on submarine slopes further off-

shore and in the basinal part (Fig. 6). 

The gradual relative fall of sea-level in the

nearshore part and a rapid progradation of the zone of

shore-barrier bars with several biocalcarenite ebb-delta

bodies between the biocalcarenite bars and barriers,

gradually progrades seaward. 

Large organic build ups (bryozoans and coralli-

nacean reefs) were required to produce a large amount

of bioclasts during relative sea-level highstand (“high-

stand shedding”). This is the period, when large quanti-

ties of bioclasts are produced and transported from the

reef to the nearshore and offshore. The relative quies-

cence after the tectonic shock in the source area of the

siliciclastic material, as well as in the reef and fore-reef

Fig. 6  Schematic outline of sedi-

mentation during the Baden-

ian age in transgressive and

regressive conditions by dif-

ferent synsedimentary tecton-

ics in a nearshore and basinal

part.



289VeliÊ, Tiπljar, DragiËeviÊ & BlaπkoviÊ: Shoreline Cross-bedded Biocalcarenites (Middle Miocene)...

zone and the back-reef platform, followed by the chan-

ge in hydrodynamic conditions, results in termination

of the fast grain avalanche or grain fall transport of the

bioclastic and siliciclastic material. In conditions of low

sedimentation rates in the shoreface and offshore-tran-

sition zone above the storm-weather wave base, and

also on the spacious platform, the destruction of the top

of cross-bedded sediments and foresets takes place. The

high-energy conditions in the shoreface-zone result in

formation of the subaqueous dunes. Well-sorted detritus

is then redeposited without the fine-grained matrix, in

the shape of variously thick low-angle cross-bedded

units (Figs. 2 and 4), which used to indicate high-ener-

gy and relatively shallow water at the level of breaking

waves (ELLIOT, 1986). In the foreshore-shoreface-off-

shore environments, the described mechanism of sedi-

mentation, with numerous repetitions of the preparatory

and main phases, enabled formation of a wide zone of

the cross-bedded biocalcarenite sedimentary bodies of

large dimensions. 

Variously located bodies of the cross-bedded biocal-

carenites along the margin of Mt. Psunj were deposited

in different nearshore and offshore environments: there

are prograding biocalcarenite shore-barrier bars, sub-

aqueous dunes, ebb-deltas and the fluvial- or tidal-dom-

inated deltas with trough cross-bedded channel fills or

with the mouth sand bars. In the basinal - distal - part of

the depositional area, the Badenian biocalcarenites

occur as turbidite members, i.e. Ta - c intervals of the

Bouma sequences. Namely, a part of the biodetritus

was transported by gravitational flows along the distrib-

utary submarine channels and canyons in the deeper

basinal part where it was deposited, together with other

detritus as calcarenaceous sandstones or biocalcarenites

of Ta-c intervals of the Bouma sequences within the tur-

bidite fans (e.g. between the Badenian sediments and

Sarmatian and Lower Pannonian ones on the western

slopes of Mt. Psunj in the OkuËani-Pakrac-Novska area

(BLA©KOVI∆ et al., 1982) and in the oil wells of the

oil fields Obod, Ladislavci and BeniËanci east from Mt.

Psunj in the Drava depression (TI©LJAR, 1993). 

4. GEOMETRY OF THE BIOCALCARENITE

SEDIMENTARY BODY AS A WHOLE

The biocalcarenite lithofacies has significant out-

crop dimensions. In the Podvrπko -©njegaviÊ area on

the SE slopes of Mt. Psunj (Fig. 1), the length of the

cross-bedded biocalcarenite sedimentary body (mea-

sured parallel to the direction of transport that was

determined by measuring the foreset dip directions) is

in the 1500-2000-metre range. Due to dispersed dip

directions of the foresets, the fan-shaped sedimentary

body is interpreted with the lensoid transversal and cli-

no-form - clinostratified longitudinal cross-sections.

The vertical dimension of the cross-bedded biocal-

carenites on outcrops with eroded surfaces is approxi-

mately 40 m.

Data on the subsurface geological structure of the

Poæega subdepression (NAJDENOVSKI & UDJBI-

NAC, 1980; NAJDENOVSKI, 1988) were made use of

in the reconstruction of the distribution of the biocal-

carenite lithofacies in areas covered by the younger

sediments. According to previous authors, there are sig-

nificant faults along the eastern margin of Mt. Psunj

and on the SE margin of Mt. Papuk - within the area of

both studied locations. The throw of these faults at the

Tertiary basement level (PT) is 1300 m or 1500-1900 in

places, while the Miocene sediments in the Podvrπko

area are supposed to be approximately 1300 m thick. In

the NW part of the Poæega subdepression, close to the

margin of Mt. Papuk, over 100 m of Miocene sediments

in supposed. Towards the centre of subdepression, the

thickness of Miocene sediments suddenly reaches 900

m. 

Such a great thickness of Miocene sediments along

the mentioned faults undoubtedly supports synsedimen-

tary tectonic activity. As a rule, this enables the progra-

dation and development of the sand bar and deltaic

depositional systems, which means that a comparatively

large longitudinal area of distribution of the described

lithofacies within the Badenian area of sedimentation

can be expected. In this specific case, this means that

the biocalcarenite lithofacies at Podvrπko and in the

similar area of the Gornji Vrhovci-Sokolina creek can

maximally reach 5 km in the E-SE direction. This is,

naturally, a supposition that has to be confirmed by

additional surface and subsurface investigations of this

area. 

5. PETROLEUM-GEOLOGY POTENTIAL OF

THE MIDDLE MIOCENE SHORELINE

CROSS-BEDDED BIOCALCARENITES

At a certain stage in the course of exploration for

accumulations of fluids - water, oil or gas, emphasis is

put on the definition of the reservoir rocks. The general

knowledge on them resulted from explorations in the

field of the geology of oil and gas pools, which has

experienced a boom since the thirties. Since the late

fifties, attention was drawn to the stratigraphic types of

traps among which one of the major groups of rocks

with adequate porosity and permeability, i.e. with good

reservoir properties, is represented by sands or sand-

stones. It was noted (MacKENZIE, 1972) that the main

factors of reservoir formation within the sandstone

stratigraphic traps are either the lateral variation of

lithologic composition and/or the breaks of their conti-

nuity. The lateral variations of porosity are mostly the

direct consequence of depositional environment, and to

a lesser extent they were caused by the post-deposition-

al processes of selective dissolution of the fossil debris

and less stable mineral grains and of cementation. The

aforementioned was, for instance, confirmed by the

works of CLEVELAND & MOLINA (1990). Within

the Cretaceous-Oligocene pools of the Cańo Limoń

field in Columbia, they documented large variations of



290 Geologia Croatica 53/2

both the architecture of the sandstone sedimentary bod-

ies and of the reservoir quality within the shoreline and

sand bar systems. 

After LeBLANC (1972), the genesis of sandstones

can be observed in the three most typical depositional

environments. The second one described comprises

transitional environments of clastic sedimentation

arranged in order from periphery to the centre of a

depositional basin, wherein deltaic models and coastal-

interdeltaic models are discerned. Cross-bedded biocal-

carenites on the slope of Mt. Psunj should accordingly

be put into the coastal-interdeltaic models, for which

LeBLANC (1972) emphasises their importance for

hydrocarbon accumulation. Namely, similar conclu-

sions were reached by several groups of geologists

working for example in the Gulf Coast region, south-

western Louisiana, upper Texas coast, Georgia, New

England, northern Dutch, etc. In a trend of described

tendencies of exploration for stratigraphic traps, SER-

RA (1985) studied the possibilities of identification of

depositional environments by the means of well-logs.

He managed to differentiate between approximately ten

principal environments, among which the most interest-

ing in this case is the shallow (siliciclastic) sea environ-

ment characterised by detrital deposits in moderate

water depth (10-200 m), or on a nearshore continent

under tides, waves, wind, longshore currents, or storms

as dominant sediment-moving forces. It is not always

easy to distinguish between the shallow siliciclastic and

the deltaic environments according to well log respons-

es and characteristics (SERRA, 1985). Examples are

shown of composite-log and dipmeter results taken in

the Powder River Basin and in the Godavari Basin in

India. This illustrates that the rocks studied in this paper

are the globally important HC reservoirs, and are exclu-

sively treated as such - i.e. classified in a separate

group. 

It also deserves to be mentioned that the hydrocar-

bon-bearing potential of shoreline cross-bedded carbon-

ate rocks was recognised even earlier. LEVORSEN

(1956) for instance, stated that the cross-bedding may

often be seen, however, on the weathered surfaces of

clastic carbonate rocks. The rocks formed in this way

are likely to be porous and therefore be good reservoir

rocks, and they probably form a larger proportion of the

carbonate reservoir rocks than is generally realised. The

most detailed classification was made by RITTEN-

HOUSE (1972). It can serve as a guide and will there-

fore be briefly explained. Firstly, all of the stratigraphic

traps are classified in the two major groups - the ones

that are not connected with unconformities and the

unconformity-related ones. The first group is of interest

here. It is subdivided in two - facies traps (I) and diage-

netic traps (II). The facies traps (I) are formed either of

current-transported reservoir rocks (A) or of ones that

were not current-transported (B). The genesis of reser-

voir rocks by current transport is possible in seven envi-

ronments, out of which the fifth one is interesting in

this case. This, nondeltaic coastal environment of depo-

sition is likely to be the one in which the Badenian

cross-bedded biocalcarenites in the Podvrπko area were

deposited. 

After many years of exploration through subsurface

mapping, well-log interpretation (primarily of the spon-

taneous potential curve) and the stratigraphic interpreta-

tion of the seismic data ©IMON (1980) interpreted the

depositional environment of the Sava group (a large

lithostratigraphic unit that encompasses sediments of

approximately Upper Pannonian and Pontian age) in the

Pannonian basin of northern Croatia. He applied the

model of the so-called “concurrent deposition” of chan-

nel sediments and a concept of the so-called “sub-sea

(sub-lake) fan”. The discovered outcrops of the Middle

Miocene (Badenian) delta and barrier-bar sediments

partially corroborate such results, and they justify mod-

ern attempts to direct the HC exploration in Croatia

more firmly to the stratigraphic traps. Naturally, this is

the case of the relatively more modest, smaller bodies

(several hundreds of metres in thickness and a few kilo-

metres in length) as compared to the ones described by

©IMON (1980), which is likely to be a consequence of

the fact that the genesis of the described cross-bedded

sedimentary bodies is connected to the different deposi-

tional environment with a probably smaller sedimentary

source area. 

It is characteristic that PIKIJA et al. (1993), while

exploring the Miocene sediments of the pools of Croat-

ia’s biggest gas fields - Molve and Kalinovac (located

close to the Hungarian border), determined that the six

facies units can be defined at depths below 3000 m. The

facies C predominates. It is composed of the Badenian

biolithites and reef and fore-reef biocalcarenites to bio-

calcrudites, mostly deposited in high-energy environ-

ments. 

The results stated above were achieved by investi-

gations at locations with representative outcrops. Sever-

al specimens for porosity measurements were taken at

Podvrπko on the same occasion. The results were more

than encouraging, because it was found that the porosi-

ty measured parallel to the sedimentary structures is

18.3%, and that perpendicular to the structures was

lower as expected - 15.14%. 

In many of the marginal parts of the inselbergs in

the Drava-Sava interfluve, as well as south of the Sava

river (all in the southern part of the Pannonian basin

that is in Croatia), sediments of the same time-span

were determined. They have similar, but less pro-

nounced sedimentological characteristics and different

geological and geomorphological characteristics of the

sedimentary source area. It is therefore possible to sup-

pose the strike of sequences of differently sized delta

and barrier-bar biocalcarenites, mostly based on the

palaeogeographic and palaeotectonic reconstruction.

The last remark is a justification of the above petrole-

um-geological text. Even more so considering the

results like the ones in the paper from PIKIJA et al.

(1993). Since these sediments have the significantly

increased porosity and permeability that, together with



291VeliÊ, Tiπljar, DragiËeviÊ & BlaπkoviÊ: Shoreline Cross-bedded Biocalcarenites (Middle Miocene)...

other characteristics (lateral and vertical lithologic vari-

ability, isolation by the basal, lateral and overlying

massive fine-grained sediments acting as the seal rocks,

structural position and tectonic fabric), favours the for-

mation of traps, it is concluded that the search for new

fluid pools should also be targeted at them. The explo-

ration should result in definition of the size, shape and

palaeogeographic orientation of these sedimentary bod-

ies and their relations to the neighbouring facies, as

well as of their porosity and permeability distribution,

firstly at the surface and then subsequently at depth,

using geophysical and geochemical methods and finally

the drilling. 

6. DISCUSSION AND CONCLUSION

Sedimentological interpretations of cross-bedded

sedimentary bodies often occur in the literature. This is

especially true for the one example that would have

more or less similarity with the subject of this paper in

terms of their architecture, internal organisation and

composition. 

The Oligo-miocene cross-bedded calcarenites on the

Northern island of New Zealand, are mostly composed

of the bioclasts of bryozoans, echinoids and benthonic

foraminifers with minor proportion of the corallinacean

bioclasts. These where interpreted in terms of subaque-

ous dunes by ANASTAS et al. (1997). The prominent,

mostly undirectional large-scale cross-stratification was

interpreted as a consequence of the migration of sub-

aqueous dunes on the sea-floor at depth of 40-60 m.

The authors explain that such dunes were formed by

strong tidal currents that flowed parallel to the sea coast

and were combined with oceanic currents. Each of the

defined cross-bedded sets was formed by a differently

curved 3D-dune in conditions of very variable water

current regime due to the changes in strength of the

tidal and sea-currents, as well as of the variations in

influx and transport of the bioclastic detritus. 

The dimensions, architecture and internal organisa-

tion of the Miocene cross-bedded biocalcarenite sedi-

mentary bodies treated in this paper have many more

similarities in the literature in the examples of the silici-

clastic cross-bedded sand bodies. Out of numerous

papers, the following are singled out because the inter-

pretations of depositional environments presented in

them could, according to our views, be applied in the

interpretation of the formation of the Badenian cross-

bedded biocalcarenites on the hill-sides of the moun-

tains within the Pannonian basin. 

An important characteristic of the tide-dominated

deltas, in contrast to the fluvial-dominated ones is that

they do not have a pronounced delta-front because the

majority of the sediment is accumulated in a very wide

area, according to EINSELE (1992) by the deposition

of large masses of the trough cross-bedded sands and

sandstones with ripples. Such sands are deposited either

in the shallow sea of the estuary mouths, or in the

neighbouring deeper environment of a wide submarine

delta platform. Differently from the ones in the fluvial-

dominated deltas, the sands are here not positioned in

the discrete and isolated mouth bars, but are rather

repeatedly reworked and redistributed by tidal currents

in the elongated bodies positioned perpendicular to the

coastline. That is why they form the elongated sub-par-

allel sand ridges in places between the estuary distribu-

tion channels of the river mouths, and in the deeper -

submarine part of the delta platform. Although the

tidal-dominated estuarine deltas usually show a weak

progradation, the delta complex as a whole gradually

advances in a seaward direction. 

The approximately ten metres thick trough cross-

bedded sands that cover the pro-delta offshore mud, and

are overlain by the planar cross-bedded sands with fore-

sets of a small dip angle, were explained by GAL-

LOWAY & HOBDAY (1983) as a consequence of the

transport and constant progradation of sands in the fore-

shore/coastal barrier sand ridges within a wide-spread

depositional system of a wave-dominated delta. 

Large masses of the trough cross-bedded sands are

interpreted by GALLOWAY & HOBDAY (1983) as

the tidal sand ridges on the pro-delta platform of a tidal-

dominated delta.

The analysed outcrops in the Podvrπko - © n j e g a v i Ê

area (Figs. 2-5) are located in the gorge of a creek and

along the road that goes roughly perpendicular to the

crystalline core of Mt. Psunj. Due to the poor exposure

of terrain, especially because of the too small outcrops

parallel to the crystalline core, and also because of the

influence of the synsedimentary tectonics on deposi-

tional system, it remains to be clear which of the depo-

sitional models described above could be applied in an

explanation of these cross-bedded biocalcarenite sedi-

mentary bodies. Considering the relevant data on the

composition, sedimentary structures and shape of sedi-

mentary bodies, as well as the very important role

played by the synsedimentary tectonics and variations

in palaeogeomorphology, our interpretation given

above has been little different from the simple applica-

tion of the one of described depositional models. 

The cross-bedded biocalcarenites in the Podvrπko -

©njegaviÊ area on the SE slope of Mt. Psunj at the mar-

gin of Poæega subdepression, shown in Figs. 2-5, are

interpreted as parts of shoreline-shoreface large sand

bar bodies, partly 3D subaqueous dunes, characterised

by a steeply inclined foreset (20-35°) and rapid progra-

dation, that were preserved from redeposition. Between

large scale cross-bedded biocalcarenites thick low-

angle cross-bedded units variously occur composed of

well-sorted detritus without the fine-grained matrix

with erosion base (Figs. 2 and 4). This indicates high-

energy redeposition of sand bodies in relatively shallow

water at about the level of breaking waves. 

In the shoreface zone with the large masses of most-

ly bioclastic detritus ebb-deltas with seaward inclined

foresets were formed between the bars or subaqueous

dunes. Cross-bedded biocalcarenites with the landward



292 Geologia Croatica 53/2

inclined foresets were not found in the Podvrπko- © n j e-

gaviÊ area.

Due to the very complicated shoreline and variable

morphology of the nearshore, shoreface and offshore

area, together with the intermittent synsedimentary tec-

tonic pulses and the consequent frequent changes in the

rate of sedimentary influx and rate of sedimentation and

in the rate of progradation, there were sudden changes

in conditions and environments of sedimentation along

the coastline, and especially in direction of the sea. Par-

allel to the predominant accumulation of biodetritus on

the back-reef platform, reef and fore-reef shoals and in

the shoreface area, submarine fans and/or turbidite fans

are formed in the deeper offshore and basinal part. This

was partly caused by tectonic uplift of the land area -

the crystalline massif of Mt. Psunj and the shallowest

parts of biohermal reefs and reef - fore-reef shoals that

were closest to the coast, but also by the faulting and

subsidence of the nearshore and offshore area. In this

way, the rapid progradation of bioclasts and a compara-

tively steep inclination of foresets were preserved with

similarities to Gilbert-deltas. 

Regarding the petroleum-geological reservoir char-

acteristics, the described sediments are correlated with

numerous large oil and gas pools around the world and

put in a separate group - reservoirs formed by current

transport. 

Sediments of the same geologic age and of similar

sedimentological characteristics are also found in other

places in Croatia - on the margins of inselberg massifs

between the Drava and Sava rivers and south of Sava

river. Because of the supposed size and contacts with

neighbouring facies, it would be wise to direct the

future search for the new oil and gas pools to these

objects. 

Acknowledgements

This work was supported by Ministry of Science

and Technology of the Republic of Croatia through pro-

jects No. 195005, No. 195018 and No. 195021. We

wish to thank to Dr. Orsolya SZTANÓ and to Dr. Da-

vor PAVELI∆ for critical reading of this contribution.

The laboratory measurements of porosity were per-

formed by the INA-Naftaplin Co., Zagreb, and authors

appreciate the kind help of Jasna TADEJ, M.Sc. in this

sense.

7. REFERENCES

ANASTAS, A.S., DALRYMPLE, N.P.J. & NELSON,

C.S. (1997): Cross-stratified calcarenites from New

Zealand: subaqueous dunes in a cool-water Oligo-

Micene seaway.- Sedimentology, 44, No. 5, 869-

892.

BLA©KOVI∆, I., TI©LJAR, J. & VELI∆, J. (1982):

Litofacijelne znaËajke tortonskih naslaga u podruËju

OkuËani-Pakrac-Novska.- Geol. vjesnik, 35, 71-86.

BLA©KOVI∆, I., DRAGI»EVI∆, I., TI©LJAR, J. &

VELI∆, J. (1985): Badenian submarine fan-delta in

the Mt. Psunj (Croatia).- 6th IAS European Region-

al Meeting. Abstracts & Poster Abstracts, 5l8-552,

Lleida.

CLEVELAND, M.N. & MOLINO, J. (1990): Deltaic

Reservoirs of the Cańo Limoń Field, Colombia,

South America.- In: BARWIS, J.H., McPHERSON,

J.G. & STUDLICK, J.R.J. (eds.): Sandstone Petro-

leum Reservoirs. Springer-Verlag, New York, Ber-

lin, Heidelberg, London, Paris, Tokyo, Hong Kong,

281-315.

EINSELE., G. (1992): Sedimentary basins. Evolution,

facies and sediment budget.- Springer-Verlag, Ber-

lin, 628 p.

ELLIOTT, T. (1986): Clastic shorelines.- In: READ-

ING, H.G. (ed.): Sedimentary Environments and

Facies.- Blackwell, Oxford, 155-188.

GALLOWAY, W.E. & HOBDAY, D.K. (1983): Ter-

rigenous clastic depositional systems - applications

to petroleum, coal, and uranium exploration. Sprin-

ger, New York, Heidelberg, 423 p.

HAQ, B.U., HARDENBOL, J. & VAIL, P.R. (1987):

Chronology of fluctuating sea-level since Triassic.-

Science, 235, 1156-1167.

JAMI»I∆, D. (1989): Osnovna geoloπka karta SFRJ

1:100000. List Daruvar, L33-95.- Geol. zavod, Zag-

reb (1975-1988), Sav. geol. zavod, Beograd.

JAMI»I∆, D. & BRKI∆, M. (1987): Osnovna geoloπka

karta 1:100000. List Orahovica L33-96.- Geol. za-

vod Zagreb (1971-1986), Sav. geol. zavod, Beo-

grad.

JAMI»I∆, D., BRKI∆, M., CRNKO, J. & VRAGO-

VI∆, M (1987): Osnovna geoloπka karta 1:100000.

TumaË za list Orahovica L33-96. Geol. zavod, Za-

greb (1986), Sav. geol. zavod, Beograd, 72 p.

JAMI»I∆, D., VRAGOVI∆, M. & MATI»EC, D.

(1989): Osnovna geoloπka karta 1:100000. TumaË

za list Daruvar L33-95.- Geol. zavod, Zagreb

(1988), Sav. geol. zavod, Beograd, 55 p.

KOVA»EVI∆, S. & MUJAGI∆, S. (1975): GeofiziËka

ispitivanja Poæeπke kotline.- Nafta, 1, 3-12, Zagreb.

LEBLANC, R.J. (1972): Geometry of sandstone reser-

voir bodies. - Am. Assoc. Petrol. Geol., Mem., 18,

155-212, Tulsa.

LEVORSEN, A.I. (1956): Geology of petroleum.-

W.H. Freeman and Company, San Francisco, VII+

703 p.

MacKENZIE, D. (1972): Primary stratigraphic traps in

sandstones.- In: KING, R.E. (ed.): Stratigraphic Oil

and Gas Fields-Classification, Exploration Methods,



293VeliÊ, Tiπljar, DragiËeviÊ & BlaπkoviÊ: Shoreline Cross-bedded Biocalcarenites (Middle Miocene)...

and Case Histories.-Am. Assoc. Petrol. Geol.,

Mem., 16, 47-63, Tulsa.

MILJU©, P. & VUGRINEC, J. (1977): Neke osnovne

crte geoloπke grae sjevernog dijela Hrvatske i

karakteristike nakupljanja ugljikovodika.- Nafta, 7-

8, 425-440, Zagreb.

NAJDENOVSKI, J. (1988): Dubinski geoloπki odnosi i

razvitak struktura u tercijarnim sedimentima Poæeπ-

ke kotline.- Unpublished PhD Thesis, University of

Zagreb, 146 p.

NAJDENOVSKI, J. & UDJBINAC, Æ. (1980): O tek-

tonici, osobito o dubinskim strukturnim odnosima

Poæeπke kotline s osvrtom na naftoplinonosnost

(Panonski bazen).- Nafta, 5, 223-235, Zagreb.

PAVELI∆, D. (1998): Taloæna evolucija slatkovodnog

donjeg i srednjeg miocena sjeverne Hrvatske na

temelju analize facijesa.- Unpublished PhD Thesis,

University of Zagreb, 149 p.

PAVELI∆, D., MIKNI∆, M. & SARKOTI∆ ©LAT, M.

(1998): Early to Middle Miocene facies succession

in lacustrine and marine environments on the south-

western margin of the Pannonian basin system

(Croatia).- Geologica Carpathica, 49, 433-443.

PIKIJA, M., ©IKI∆, K., TI©LJAR, J. & HRABAK, N.

(1993): Miocene formations of the Molve-Kalino-

vac area (North Croatia).- Nafta, 12, 665-671,

Zagreb.

PRELOGOVI∆, E., JAMI»I∆, D., ALJINOVI∆, B.,

VELI∆, J., SAFTI∆, B. & DRAGA©, M. (1995):

Dinamika nastanka struktura juænog dijela Panon-

skog bazena.- 1. hrvatski geoloπki kongres, Opatija

18-21.10.1995., Zbornik radova, 2, 481-486, Za-

greb.

PRELOGOVI∆, E., SAFTI∆, B., KUK, V., VELI∆, J.,

DRAGA©, M. & LU»I∆, D. (1998): Tectonic activ-

ity in the Croatian part of the Pannonian basin.-

Tectonophysics, 297, 283-293.

RITTENHOUSE, G. (1972): Stratigraphic-trap classifi-

cation.- In: KING, R.E. (ed.): Stratigraphic Oil and

Gas Fields-Classification, Exploration Methods, and

Case Histories.- Am. Assoc. Petrol. Geol., Mem.,

16, 14-28, Tulsa.

SERRA, O. (1985): Sedimentary environments from

wireline logs.- Schlumberger, 211 p.

©IMON, J. (1980): Prilog stratigrafiji i taloænom sus-

tavu pjeπËanih rezervoara Sava-grupe naslaga mla-

eg tercijara u Panonskom bazenu sjeverne Hrvat-

ske.- Unpublished PhD Thesis, University of Za-

greb, 66 p.

TI©LJAR, J. (1993): Sedimentary bodies and deposi-

tional models for the Miocene oil-producing areas

Ladislavci, BeniËanci and Obod (Croatia).- Nafta,

10, 531-542, Zagreb.

Manuscript received February 18, 2000.

Revised manuscript accepted November 13, 2000.



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