The timing and evolution of the post-glacial transgression across the Sea of Marmara shelf south of Istanbul
|Author(s)||Eris K1, Ryan W2, Cagatay M1, Sancar U1, Lericolais Gilles3, Menot G4, Bard E4|
|Affiliation(s)||1 : Tech Univ Istanbul, Fac Mines Emcol, Geol Dept Ayazaga, Istanbul, Turkey.
2 : Columbia Univ, Lamont Doherty Geol Observ, Palisades, NY 10964 USA.
3 : IFREMER, Lab Environm Sedimentaires, Port En Bassin, France.
4 : Coll France, CEREGE, UMR 6635, Paris, France.
|Source||Marine Geology (0025-3227) (Elsevier), 2007-09 , Vol. 243 , N. 1-4 , P. 57-76|
|WOS© Times Cited||49|
|Keyword(s)||Sapropel, Delta, Marmara Sea, Holocene, Sea level, Seismic stratigraphy|
|Abstract||High-resolution reflection seismic profiles with core analyses of sedimentary sequence near the Sea of Marmara (SoM) entrance to the Strait of İstanbul (SoI, Bosphorus) provide detailed record of sealevel changes since the Late Glacial Maximum (LGM). The sequence is deposited over the LGM erosional surface at a maximum depth of -105 m. It includes seven seismic units that can be confidently correlated with 14C-dated sedimentary units in the cores. Unit 6 represents levee deposits of the paleo-SoI channel that was deposited by a Black Sea outflow during 11.2-10.6 kyr BP. The reflection surfaces at base of Unit 5 and 4 correspond to wave-cut terraces at -71and -63 m, respectively, and are estimated to be 10.6 and 9.8 kyr BP. The seismic Unit 2, overlaying a mud drape (Unit 3), comprises deltaic sediments that was deposited during 6.400-3200 yr 14C BP. Isopach map and forset directions of the deltaic unit indicates that the delta was sourced from Kurbağalıdere River. Depositional period of the delta is subdivided into two stages in response to changes in the 49 balance between sealevel change and sediment supply rates: a progradational and an aggradational stages. The progradational stage prevailed during 6.4-4.7 kyr BP when the sealevel rise decelerated and there was a high sediment input from the drainage area of the Kurbağalıdere River. An aggradational stage developed during 4.7-3.2 kyr BP and indicates that the delta grew during faster sealevel rise when the rate of sediment input was relatively decreased. The onset of delta deposition at 6.4 kyr BP is marked in the SoM by termination of the early Holocene Sapropel deposition and the aggradational stage overlaps with the late Holocene Sapropelic unit deposited on the shelf areas. Our finding contradicts the hypothesis of Hiscott et al. (2002) and Aksu et al. (2002) that this delta was sourced from the Black Sea and that it indicates a persistant Black Sea outflow since 10 kyr BP.|