The Pannonian Basin is an intraorogenic extensional region floored by a complex system of Alpine orogenic terranes and oceanic suture zones. Its formation dates back to the beginning of the Miocene, and initial fluvial-lacustrine deposits pass into shallow to open marine strata, including a large amount of calc-alkaline volcanic materials erupted during the culmination of the synrift phase. The onset of the postrift phase occurred during the Late Miocene, when the basin became isolated and a large Pannonian lake developed. Early lacustrine marls are overlain by turbiditic sandstones and silts related to a progradational shelf slope and a delta plain sequence passing upward into alluvial plain deposits and eolian sands. A remarkable nonconformity at the top of lacustrine strata associated with a significant (4–7 my) time gap at large parts of the basin documents a neotectonic phase of activity, manifested by regional strike-slip faulting and kilometer-scale differential vertical movements, with erosion and redeposition. Subsidence and burial history modeling indicate that Middle and Late Miocene, fairly organic-rich marine and lacustrine (respectively) shales entered into the oil-generation window at about the beginning of the Pliocene in depocenters deeper than 2.5–3 km, and even reached the wet to dry gas-generation zone at depths exceeding 4–4.5 km. Migration out of these kitchens has been going on since the latest Miocene toward basement highs, where anticlines and flower structures offered adequate trapping conditions for hydrocarbons. We argue that compaction of thick sedimentary piles, in addition to neotectonic structures, has also been important in trap formation within the Pannonian Basin.

Cretaceous deposits in the wider area of Mokra Gora village (western Serbia) were studied previously during basic, thematic mapping and detailed metallogenic investigations. These former studies neither distinguished the clearly defined formations, nor defined the lower rank lithostratigraphic units. The oldest Cretaceous formation in the area of Mokra Gora, the 'Basal series', lies above peridotite and serpentinite and below the 'Hemipelagic series' (RADOIČIĆ 1995, and references therein). This study preliminary defines the 'Basal series' as a formation and proposes the lithostratigraphic term 'Kotroman Formation'. The stratigraphic column of the Kotroman Formation consists of three separate members of lower rank. The ferruginous sandstone and conglomerate of the Kamišna Member occupy the lower part, nodular bedded marly limestone of the Uroševići Member are in the middle part and thin bedded bioclastic limestone of the Jatare Member made up the upper part of the formation. Fossils are represented by sporadic assemblages of mollusks, foraminifers, algae, brackish water charophytes and ostracodes, which indicate an Albian-Cenomanian age of the formation

Abstract:Micropalaeontological and biostratigraphical studies included Campanian-Maastrichtian complexes from five oil exploration wells drilled in northern Serbia (Vojvodina): the first is a carbonate-clastic complex and second is a complex containing ophiolites intercalated with hemipelagic and pelagic sediments. Within the studied complexes, rich associations of planktonic and benthic foraminifera, calcareous nannoplankton, palynomorphs, as well as shallow and deep-water fossil detritus were determined. The presence of relatively rich associations of planktonic foraminifera allowed recognition of two biozones: the Globotruncana ventricosa Zone, observed in the sediments of the carbonateclastic complex and the Gansserina gansseri Zone, observed in both complexes. Except biozones, based on documented index species, for some units in both complexes, larger benthic foraminifera species had special biostratigraphical value, and in some of them, the calcareous nannoplankton zones were recognized. The studied complexes represent deep-water formations, generated in oceanic island arc and trough zones. The presence of limestones, which originate from destroyed rudist reefs, is explained by transfer by means of gravitational transport mechanisms of shallow-water sediments to deep-water depositional environments. In this paper, the results of more detailed biostratigraphical and palaeo-ecological studies of foraminifera associations in Campanian-Maastrichtian complexes in Vojvodina are presented. Combined with lithological studies, seven units were determined within the complexes. The obtained results are important as a part of multidisciplinary, regional exploration of both complexes, generated in specific geological conditions, that today constitute a part of the pre-Neogene basement complex in the southeastern part of the Pannonian Basin. The CampanianMaastrichtian carbonate-clastic complex represents sedimentary cover of the Eastern Vardar Ophiolitic Unit, while the ophiolites intercalated with hemipelagic and pelagic limestones belongs to the Sava Zone.

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