A high-resolution seismic study in Sakarya Delta and Submarine Canyon, southern Black Sea Shelf

摘要

Fligh-resolution seismic reflection profiles obtained from the Sakarya Delta have revealed the existence of three seismic units. Unit I is the subaqueous prodelta deposits of the Sakarya River and is separated from Units 2 and 3 by a major erosional surface. It is an oblique progradational delta sequence and best developed to the west of the Sakarya River mouth. The erosional surface extends over the whole shelf and was produced during the lowstand of' sea level before the latest rise in the Black Sea. Unit 2 represents the lowstand sedimentary wedge deposited at the shelf edge during that time and is covered by a thin drape of Unit 1. The basement Unit 3 consists of folded-faulted acoustically reflective strata and is cut by an erosional surface at its upper boundary where it is overlain by Unit I on the shelf. The boundary between Units 2 and 3 delineates the paleo-shoreline during the lowstand period and Occurs in a water depth of about 105 m. The rise of the sea drowning the shelf area of the Black Sea is recorded by the thin drape deposited over the erosional surface separating Unit I from Units 2 and 3 at around 7-8 kyr BP. The submarine canyon in front of the Sakarya Delta extends to 1500-2000 in water depth and includes two canyon heads. The occurrence of steep scarps of the canyon walls and the lateral displacement of canyon heads from the main canyon axis coincide with a major fault zone. Tectonic and submarine erosion processes appear to have been important in the initiation and development of this canyon system. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 36]