ABSTRACT: Stratigraphy and Evolution of the Danube Basin, Northwestern Hungary

P. G. Teleki, B. Bardocz, R. E. Mattick

The stratigraphy of basement rocks and of the Neogene sequences, and the Neogene evolution of the Danube basin in northwestern Hungary was investigated by using lithostratigraphic, chronostratigraphic, and biostratigraphic correlations of cores and well logs, and by interpreting seismic reflection profiles. The study was part of a project that evaluated the petroleum basin's potential.

The basement is comprised of two terranes whose geologic development differ in space and time prior to the middle Miocene. The terrane in the western part of the basin, composed principally of Paleozoic metamorphic rocks, belongs to the Austroalpine domain. The eastern part of the basin, dominated by Triassic dolomites, belongs to the allochthonous Pelso block of South Alpine origin. Both parts of the basement were subjected to folding and overthrusting in the Early Cretaceous, followed by welding of the two blocks probably during Oligocene, followed by extension during the middle Miocene time.

In the Senonian section, prior to the fusion of the terranes, carbonate reefs, separated by shallow basins, developed on Triassic basement highs on the Pelso block. The thickness of the sequences reached 600-1000 m. During the Eocene-early Oligocene, most of the Senonian section eroded, except in grabens.

Rapid, differential subsidence accompanied by synrift (breccia-conglomerate) sedimentation in the Karpatian (late early Miocene) marks the initial extensional phase. The first marine transgression, in the early Badenian (middle Miocene), entered the basin from the southwest and resulted in the deposition of sandstones, siltstones, and marls in a rapidly subsiding basin, in which shelves were incised by canyons. In the middle Badenian, a basin-wide regression took place as the central part of the basin tilted northwestward and additional troughs developed. Acidic volcanism, lasting until the late middle Miocene, accompanied this regression. The basin became filled with turbidites, then marls interbedded with andesitic flows, volcanic agglomerates, and tephra. Lithothamnion reefs formed on the fringe of the basin. The marine environment gradually became brackish, then lacustrine by the early late Miocene, time, as indicated by lithologic successions and the appearance of endemic fauna. In the late Micoene-Pliocene, alluvial-deltaic sedimentation became dominant along with episodic basaltic volcanism.

Prospective oil and gas plays are Triassic anticlines, faulted Senonian sequences, lower Badenian onlap and transgressive sand pinch-outs, Sarmatian turbidites interbedded with volcanic rocks, Badenian bioherms and channel sandstones, and Cretaceous reefs. Source rocks are Miocene marls.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990