Abstract: Neogene Depositional Environments, Structures and Hydrocarbon Plays in the Northern Croatia (Pannonian Basin)

LUCIC, DUBRAVKO, MATE DRAGAS, EDUARD PRELOGOVIC

The considered area is at the southern margin of the Pannonian Basin. Structural evolution can be subdivided into the synrift (Oligocene-early Miocene) and postrift (middle to late Miocene) phase of subsidence.

Neogene deposits in the area are deposited on complex substrata of Mesozoic and/or Paleozoic rocks which exhibit Dinaric, Alpine or Carpathian affinity.

The first phases of rifting were characterized by Karpatian trachyandensite volcanic activity. Initially formed grabens (pull-apart) were continuously filled with elastic deposits. During Badenian the sea reached a large extent, and coral reefs and "rhodolitic platforms" were widespread at the margins of the largest depressions (Sava and Drava basins). Simultaneously in the central parts, true deep-water environments with turbidites dominate. Basalt-andensite-dacite-rhyolite association was produced by volcanic activity.

In post-rift phase, during Sarmatian according to the global sea level fall and tectonic activity, the region was in many places elevated above the water table. During Pannonian-Pontian, depressions were finally filled up with fresh-water sediments (shallow lacustrine deposits, tidal flats, small deltaic system, etc.)

Hydrocarbon plays exist in the Neogene basin-fill deposits and in the apical parts of the Mesozoic or Paleozoic basement. Hydrocarbons mainly migrated into post-Pontian transpressional structures. Oil and gas reservoirs are located in between transcurent fault zones and into structural units (en-echelon, pop-up, flower, etc.).

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria