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Interpretation of paleontological data in papers published by Academician V. Kranjec
Jasenka Sremac

Last modified: 2017-06-19

Abstract


Extended abstract

 

Eminent scientist, academician Velimir Kranjec, who spent his whole career at the Faculty of Mining, Geology and Petroleum Engineering, significantly contributed to geological, geophysical and geochemical research of oil and gas in Croatia. It is interesting that, in his several papers on Cenozoic deposits, he integrated and systematically interpreted results of paleontological analyses, which makes these papers inevitable in basic paleontological research of Cenozoic deposits in northern Croatia, and wider Pannonian region. Paleontological analyses, combined with knowledge on tectonic processes, helped in interpretation of geological sequences and were particularly useful in study of structural-stratigraphic and stratigraphic traps in the Pannonian Basin System.

 

DISSERTATION

Already in his dissertation (Kranjec, 1969) used and synthesized paleontological data from paleontologists V. Amšel and academician V. Kochansky-Devidé. Diverse fossil flora and fauna was determined in the wider area of Tuzla. The oldest, Late Cretaceous deposits comprise indicative marine microfauna. They are overlain by Paleogene and Neogene deposits. Sedimentary deposits of Badenian (formerly: "Tortonian") and Sarmatian age comprise foraminifers, ostracods, mollusks and fish particles, while brackish and fresh-water Late Miocene sediments comprise interesting mollusks (dreiseniids and valencieniids).  Land macroflora is also present (Kranjec, 1969; Velić & Malvić, in press).

 

A number of important paleontological and stratigraphical data are available in several papers published between years 1970 and 1980, among which some are of particular interest (Kranjec et al., 1973, 1976).

 

UPPER "TERTIARY" OF THE MEDVEDNICA MT.

In study considering Miocene and Pliocene deposits from the Medvednica Mt. (Kranjec et al., 1973) authors deal with complex geological data. They critically analyze available published data on almost 3 text pages. In order to present the geological situation as clear as possible, they refer to four carefully chosen profiles, one on south-western, one on southern and two on northern side of the Medvednica Mt. (Figure 1). During their research authors tried to avoid covered and tectonically disturbed areas, and combined several smaller profiles in order to provide the complete sequence (Figure 2).

 

Figure 1: Position of four investigated profiles through Miocene and Pliocene deposits of Mt. Medvednice (Kranjec et al., 1973)

 

Figure 2: Combination of several smaller profiles in order to get the complete stratigraphical sequence at Profile I (Kranjec et al., 1973)

Paleontological data were obtained from paleontologists N. Skenderović-Sila (macrofauna), S. Mamužić-Muldini (Karpatian, Badenian and Sarmatian) and A. Sokač (Pannonian and Pontian).

Miocene deposits at research profiles transgressively overlie different older deposits (Late Paleozoic, Triassic).

 

Profile I

This profile is situated at south-western edge of the Medvednica Mt. (Figures 1, 2, 3) and reflects "Dolje development" of the Badenian, as described by Kochansky (1944). Miocene deposits at this profile transgressively overly Triassic dolomites. Massive Lithothamnion–limestones and maerls of "Tortonian" (today: Badenian) age are rich in fossils and were traditionally exploited in quarries (Dolje, Bizek). The most common fossils are mollusks (oysters, scallops, lucinids, corbulas, tellinas, cones, moon snails and turritelids, accompanied with echinoid genus Clypeaster. Macrofauna of argillaceous and sandy marls is different and comprises smaller scallops of the genus Amussium together with other tolerant and wide-spread mollusk taxa.

Younger, Sarmatian deposits are characterized with occurrence of bivalve genera Musculus, Mactra and Ervilia, and cerithid gastropods in younger horizons. One of the typical Sarmatian rock-types is white foliated marl (formerly known as "Tripoli").

 

Figure 3: Schematic geological map of the area around Profile I (Kranjec et al., 1973)

Sarmatian deposits are overlain by brackish Pannonian (Croatica– and Banatica–beds), with lymnaeid and planorbid gastropods, and congerians. Upper horizons comprise diverse ostracods and fish remnants.

Abichi–beds are not visible in continuation, but outcrop near-by. They comprise bivalves (Paradacna, Congeria), valencienesiid snails and ostracods.

Rhomboidea–beds outcrop at a neighboring locality, and comprise diverse ostracod fauna, congerians, lymnocardiids and advanced, shield-formed lymnaeids.

Total thickness of Miocene and Pliocene deposits at this profile is 785 m (Kranjec et al., 1973).

 

Profile II

This profile is situated at the saggital axis of the Medvednica Mt. (Figures 1, 4), and corresponds to "Čučerje Development" of the Badenian sensu Kochansky (1944).

 

Figure 4: Graphical display of the area around Profile II (Kranjec et al., 1973)

 

Different than in the area of Profile I, in this area Miocene fresh-water lake deposits overly the Paleozoic basement. The basal horizon comprises coarse-grained conglomerates, sandstones and sands. The following horizon comprises sandy clays and breccious limestones with dreiseniid coquines. Uppermost part is composed of marls and clays. Volcanic activity was early recognized by R. Mutić (Mutić, 1969, from Kranjec et al., 1973). Coal measures were sporadically found in the wider area. Microfauna was determined by S. Mamužić-Muldini and L. Šikić. Stratigraphic age of these deposits is yet not completely solved – at the beginning described as "Oligomiocene", and later as Karpatian (Helvetian s.str.), while today these deposits are presumed to be Ottnangian to Early Badenian in age (Kovačić et al., 2016).

Marine Badenian deposits trangressively overly lake marls and clays. Lithothamnion–limestones, maerls, conglomerates, sandstones and marls show similarity with contemporaneous deposits at Profile I Authors estimate the total thickness of 470 m for this horizon, which is significantly thicker than at Profile I.

In southern part of the profile, Sarmatian Ervilia–marls and white foliaceous marls can be found at the surface.

They are overlain with Croatica–beds of the early Pannonian, comprising typical mollusk fauna: Radix croatica Gorjanović-Kramberger, Gyraulus praeponticus Gorjanović-Kramberger, Pisidium costatum Gorjanović-Kramberger, representatives of genera Paradacna and Congeria and remnants of land flora.

Continuous transition into the late Pannonian Banatica–beds can be observed, and, among fossils, indicative are Congeria banatica R. Hörnes and Gyraulus (former Planorbis) tenuistriatus Gorjanović-Kramberger.

Upper parts of the profile are composed of Abichi–beds with typical Paradacna abichi, and loose micaceous sands with Congeria cf. rhomboidea M. Hörnes and lymnocardiids.

Total thickness of Miocene and Pliocene beds at this profile is 1790 m (Kranjec et al., 1973).

 

Profile III

This research area is situated at northern slopes of Mt. Medvednica (Figure 1). Miocene deposits at this area are today well exposed in quarries Donje and Gornje Orešje, exhibiting transgressive contact with Cretaceous basement.

Badenian deposits are developed as Lithothamnion–limestones, coarse-grained sandstones and yellow marls with scallop Amussium denudatum (Reuss). Kranjec et al. (1973) did not notice the continuous Badenian/Sarmatian transition, but, along with advanced activities in the quarries, such transition is now available at the upper part of the sequence in the quarry Donje Orešje (Pezelj et al., 2017).       Sarmatian deposits, similar as at Profiles I and II, comprise bivalve genera Mactra and Ervilia, fish scales and abundant, but fragmented particles of land flora (Ficus sp. and Quercus sp.).

Overlying Pannonian deposits are typically developed, comprising platy calcareous marls of Croatica-beds and argillaceous, darker colored Banatica–beds wirh congerians and planorbid gastropods.

Abichi-beds are developed in facies of grey marls, with typical Paradacna and Congeria species.

The youngest, Rhomboidea-beds, comprise abundant ostracods, large congerians and lymnocardiids.

Total thickness of Miocene and Pliocene beds is 985 m (Kranjec et al., 1973).

 

Profile IV

The last research profile is situated at northern slopes of Mt. Medvednica (Figure 1). Miocene deposits transgresivelly overly Early Triassic micaceous sandstones. Basal parts are sometimes represented with conglomerates. Lithothamnion–limestones, sandstones and marls are also present.

Overlying Sarmatian beds are of small thickness, and Pannonian beds outcrop sporadically; only upper horizon, Banatica–beds, is proven by fossils.

Abichi–beds comprise lymnocardiids and ostracods, and the uppermost Rhomboidea–beds at this profile comprise diverse large bivalves and land flora remnants. Coal-measures from this area were exploited at Selnica mine.

Total thickness of Miocene and Pliocene deposits at this profile is 1010 m (Kranjec et al., 1973).

 

Authors further discuss the relationships and thicknesses of different stratigraphical horizons. Significant differences were noticed in thickness of Badenian deposits, with maximum thickness in the wider area of Čučerje.  The youngest, Rhomboidea–beds, exhibit less pronounced differences.

 

Kranjec and collaborators (1976) reconstruct asymmetrical syncline at Tepčina špica-Hum profile, with Miocene deposits transgressively lying over the Cretaceous beds (Figure 5) and transgressive Miocene sequence over the Paleozoic basement at some other localities (Figure 6) .

 

Figure 5: Syncline at the profile Tepčina špica-Hum (Kranjec et al., 1973)

 

Figure 6: Miocene and Pliocene deposits transgressively

lying on Paleozoic basement in the wider area of Mlinovi (Kranjec et al., 1973)

 

In their Conclusions chapter authors emphasize the facts and significance of variable thickness of same horizons in different profiles. They point to the problems in determining the age of lacustrine deposits in the base of the Miocene transgression, which has later been proven by dilemmas of several other authors.

 

SARMATIAN AND PANNONIAN DEPOSITS OF DRAVA DEPRESSION

A group of researchers, under the leadership of V. Kranjec, published a study on Sarmatian and Pannonian deposits in the Drava Depression (Kranjec et al., 1976). They combine the carefully studied data from the previous research, paleontological, petrographical and geophysical data. Subsurface mapping yielded interesting data on oscillatory changes in lithological composition and thicknesses of the Sarmatian and early Pannonian deposits, combined with the studies from the surface data.

Thickness of Sarmatian deposits, which exceeds 400 m, is particularly interesting, and surpasses the thickness of similar contemporary deposits in the Tuzla Depression.

Early-Pannonian brackish deposits exhibit regressive features. Argillaceous limestones and limy marls are dominant along the edge of the depression, while up to 900 m thick sandstone deposits prevail in the deeper parts of the depression.

Foraminifera are the most common fossils in Sarmatian deposits. Pannonian beds comprise mollusk fauna, including lymnaeids, planorbids and congerians.

 

Figure 7: E-K diagram of the bore-hole Cabuna-9 (Kranjec et al., 1976)

Authors were eager to compile the different analytical data in order to recognize the boundaries between the stratigraphic horizons (Figure 7). The results point to the rather recognizable Badenian/Sarmatian boundary, which sometimes coincides with EK-marker Rs7. Sarmatian/Pannonian boundary is also rather well defined, often coinciding with EK-marker Rs5 or G.

At the prepared maps of Sarmatian and Pannonian deposits thicknesses, significant differences between the eastern and western part of the Drava Depression are clearly visible. This is the additional proof of rhythmic deposition and sedimentation of large amounts of sand with synchronous sinking of the central parts of the depression (Kranjec et al., 1976).

Due to their comprehensive approach, these, and many similar papers of Academician V. Kranjec and his collaborators represent the inevitable basic literature for all geologists interested in the Miocene and Pliocene deposits of northern Croatia and surrounding areas.


References:

 

Kochansky, V. (1944): Fauna marinskog miocena južnog pobočja Medvednice (Zagrebačke gore). Vjesnik Hrv. držav. geol. zav. i Hrv. držav. geol. muzeja, 2/3, 171-280.

Kovačić, M.; Mandic, O. & Tomljenović, B. (2016): Miocene paleo-lakes of the southwestern Pannonian Basin. RCMNS Interim Colloquium 2016, 20–24 May 2016, Zagreb, 11-14.

Kranjec, V. (1969): Geološka građa šireg Tuzlanskog područja. Disertacija. Institut za rudarska i hemijsko-tehnološka istraživanja. Tuzla, 282 +2. str.

Kranjec, V., Prelogović, E., Hernitz, Z. & Blašković, I. (1971): O litofacijelnim odnosima mlađih neogenskih i kvartarnih sedimenata u širem području Bilogore, sjeverna Hrvatska. Geol. vjesnik, 24, (1970), 47-56.

Kranjec, V., Hernitz, Z. & Prelogović, E. (1973): Prilog poznavanju mlađih tercijarnih naslaga Medvednice, sjeverozapadna Hrvatska. Geol. vjesnik, 25, 65-100.

Kranjec, V., Hernitz, Z., Reščec, T. & Velić, J. (1976): O sarmatskim i starijim panonskim naslagama u Dravskoj potolini. Geol. vjesnik, 29, 125-149.

Pezelj, Đ.; Sremac, J.; Kovačić, M.; Alagić, S. & Kampić, Š. (2017): Middle Miocene Badenian-Sarmatian sedimentary sequence in the area of Donje Orešje (Medvednica Mt., Croatia). 7th International Workshop "Neogene of Central and South Eastern Europe" Velika, Croatia, May 28-31, 2017, 46-47.

 

Internet source

http://info.hazu.hr/hr/clanovi_akademije/osobne_stranice/velimir_kranjec

 

 


Keywords


Academician Velimir Kranjec, Cenozoic, paleontology, Croatia

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