--> Abstract: The Geological History of the Istria ‘Depression’, Offshore Romania: Tectonic Controls on Second Order Sequence Architecture, by David Boote; #90072 (2007)

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The Geological History of the Istria ‘Depression’, Offshore Romania: Tectonic Controls on Second Order Sequence Architecture

David Boote
Consultant, London, United Kingdom

The Istria ‘Depression' or trough of offshore Romania, lies at the intersection of the trans-European, Tornquist-Teisseyre ‘Zone' and the Black Sea back arc basin, just outboard of the East Carpathian orogenic welt. It experienced an extraordinary polyphase history of subsidence, sedimentation and dramatic sediment evacuation during the late Mesozoic and Tertiary, reflecting the interplay between these three tectonic domains. It first developed as a trans-tensional rift in the Triassic- Jurassic to be compressed and deformed during the (?)end-Jurassic Cimmerian orogeny. Residual topography was filled by a west-facing continental clastic-evaporite sequence during the Neocomian. This was terminated by uplift and doming associated with Apto-Albian rifting and back-arc spreading in the western Black Sea. Post break-up subsidence and tilting of the Black Sea rift margin, led to easterly evacuation of its early Cretaceous sedimentary fill by gravity-driven mass wastage. The margin was subsequently transgressed from the east with deposition first confined within the open Istria trough and later expanding out onto the bounding highs. By the end of the Cretaceous, it had been entirely buried, only to be partially evacuated once more in the early Palaeocene and again quite spectacularly during the (?)late Eocene. The deeply incised canyon formed at that time, was rapidly filled by Oligocene-Miocene sediments, but late Miocene (Messinian?) draw-down of the Black Sea basin was reflected by yet a third period of erosional incision. Continental margin outbuilding followed during the Plio-Pleistocene with deposition of several rapidly prograding wedges. This was interrupted by a major gravity slide event and several phases of shelf-margin canyon incision and late phase of shelf margin listric faulting, reflecting the final docking of the Carpathian orogen.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece