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Seismic Stratigraphic and Seismic Geomorphologic Analysis of Deep-Water Deposits of the Turkish Black Sea

Abstract

Deep-water Cenozoic sedimentation in the Turkish sector of the Black Sea takes several forms. Seismic stratigraphic and seismic geomorphological analyses of 3D seismic data reveal that near the base of the Cenozoic section a thick package of sediment waves are observed. These deposits comprise a section approximately 800m thick. The wave length of these features ranges from 1.5-1.8km, with an amplitude of approximately 50m. These deposits are inferred to be sand poor. Sediment wave formation ends abruptly and is overlain by turbidite deposits. Discrete channels can be observed oriented east-west. Flow direction is inferred to be from west to east parallel with the paleo contour. The turbidity currents were likely sourced from the west and ran contour parallel within the study area. The basal turbidites are characterized by isolated channels followed by an expanse of weakly confined channels, all oriented west-east. Just above this section, the turbidite deposits are characterized by a distinctly bifurcational distributive map pattern. In section view these deposits are characterized by high-amplitude continuous and parallel seismic reflections. It is likely that the channels were sand-rich based on the number of avulsion nodes observed. However, the sand presence within inter-channel areas is uncertain. The turbidite-prone sections are present within an interval over 1000m thick, though they likely comprise a small net to gross within that section. Above the turbidite deposits, sourced from the west, lie mass transport deposits that appear to have been derived from the north-northwest. These deep-water deposits appear to have traversed the Black Sea for a distance of as much as 500km and are characterized by minimal internal deformation as slide deposits across a basal decollement surface. Near the terminus of these mass transport deposits, evidence for significant compression is observed and a discrete terminal wall is present. Significant thrusting into ramps with duplex folding is also observed. The sediments comprising the mass transport deposits are likely deep-water facies incorporated into the flow by events originating on the slope of the opposite side of the Black Sea.