The geological history of the Istria ‘Depression’, Romanian Black Sea shelf: tectonic controls on second-/third-order sequence architecture

摘要: The Istria ‘Depression’ or sub-basin of offshore Romania lies at the intersection the trans-European Tornquist-Teisseyre ‘Zone’ and Black Sea back arc basin, just outboard of East Carpathian orogenic welt. Its Late Mesozoic-Cenozoic succession records an extraordinary cpolyphase history subsidence sedimentation, interrupted by several quite spectacular 2nd /3rd order erosional unconformities, reflecting interplay between these teetonic domains. unconformities divide into a number stratigraphic sequences. The first developed as transtensional rift in Triassic-Early Jurassic, evolving into narrow oceanized trough later Jurassic. This was tilted west during Early Cretaceous uplift rifting Western residual Jurassic topography filled buried west-facing clastic-evaporite wedge. Aptian- Albian post-rift spreading imposed strong easterly tilt, encouraging partial evacuation its Early Cretaceous sedimentary fill gravity-driven mass wastage. incised valley topography subsequently later Cretaceous Cenozoic. During mid-Late Cenozoic, basin experienced intermittent periods to complete isolation from world ocean and significant base-level drawdown. major sea level fall occurred Eocene when the deeply incised, be healed Oligocene shales the subsequent rise. Yet another period drawdown exposure mid-Miocene With extensive shelf margin wastage erosion, followed reflooding deposition of transgressive backstepping sequence mid-late Miocene. Messinian the Mediterranean caused further falling base level. margin Was again exposed experienced widespread slumping. A marine connection re-established late Messinian. Rising eroded earlier slumped sequence lowstand prograding wedge Miocene-early Pliocene. sedimentation Plio-Pleistocene periodically interrupted canyon incision events, testifying continued climatically tectonically- imposed fluctuations. Several direct indirect tectonic factors were responsible for valley/canyon incision within Depression erosion Romanian margin. These include; (1) local structural framework (2) tilting (3) more indirect tectonically significant falls.