--> Abstract: The Interplay of Tectonics and Sedimentation During Late-Stage Subduction and Collision in the Romanian Eastern Carpathians, by P. Zweigel and Z. Sylvester; #90942 (1997).

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Abstract: The interplay of tectonics and sedimentation during late-stage subduction and collision in the Romanian Eastern Carpathians

ZWEIGEL, PETER, and ZOLTAN SYLVESTER,

Previous sedimentologic and structural studies on the oil-bearing outer Eastern Carpathians were more or less of a descriptive character. Our studies attempted a coherent tectonosedimentary model within the concept of active margin tectonics, which may guide further hydrocarbon exploration. Late Cretaceous to Miocene subduction of the floor of the Carpathian Flysch Basin beneath the Tisza-Dacia terrane led to successive accretion of deep-water sediments as flysch nappes. As a consequence of accelerated accretion in Early Miocene, piggy-back basins were formed in the forearc region which were filled with marginal marine and alluvial sediments (e.g., Doftana Molasse). Contemporaneous with shallow-water deposition in these forearc basins, sedmentation continued under deep-water conditions in the trench, as evidenced by Lower to Middle Miocene turbidites in the Subcarpathian Nappe. Middle Miocene continental collision resulted in transgression onto the foreland, in rapid reduction of water depth and in separation of the foreland basin from open oceans. This led to evaporite deposition followed by sedimentation in brackish to limnic environments. Continued shortening incorporated these 'molasse' deposits in the nappe pile, employing the evaporite horizons as decollement levels. Collisional deformation was no more restricted to the front of the accretionary wedge but affected also the hinterland, leading to folding of the piggy-back basins and partly to their accelerated subsidence. They were filled during Middle to Late Miocene, contemporaneously with newly created piggy-back basins closer to the collision front (e.g., Odaile-Soimari basin). All of them underwent successive folding as a consequence of ongoing convergence until the Quaternary.i

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