The Pannonian basin is an intra-orogenic 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. Onset of 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 unconformity at the top of lacustrine strata associated with a significant (4 to 7 my) time gap at large parts of the basin documents a neotectonic phase of activity, manifested by regional strike-slip faulting and km scale differential vertical movements, with erosion and redeposition. Subsidence and burial history modeling show that Middle and Late Miocene, fairly organic-rich marine and lacustrine (respectively) shales entered into oil-generation window at about the beginning of Pliocene in depocenters deeper than 2.5 to 3 km, and even reached the wet to dry gas generation zone at depths exceeding 4 to 4.5 km. Migration out of these kitchens has been going on since the latest Miocene towards 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 been also important in trap formation within the Pannonian basin.
ASJC Scopus subject areas
- Sociology and Political Science