Post-Glacial Terraces of the Marmara Sea and Water Exchange Periods

Abstract

Semi enclosed Marmara Sea is a passage between the Aegean Sea (Northeastern Mediterranean Sea) and the Black Sea. The Marmara Sea is connected to the Black Sea and Aegean Sea through the İstanbul Strait (Bosphorus) and Çanakkale Strait (Dardanelles), respectively. Despite the fact that the late Pleistocene-Holocene connections between the seas have been explored by many scientists, there are still uncertainties about the nature and timing of the connections. Within the scope of this study, a new approach has been displayed for post-glacial connections between the Black Sea, Marmara Sea and Aegean Sea. This study is based on 80 shallow seismic refl ection lines, multibeam bathymetric data and 15 short gravity cores collected from the northeastern shelf of the Marmara Sea (between Silivri and Golden Horn). The sea bottom and sub-bottom morphology have a highly chaotic structure at the exit of the Büyükçekmece/Küçükçekmece lagoons and further east near the Marmara-İstanbul Strait junction. This chaotic bottom and sub-bottom surface morphologies are mainly controlled by the structure of the basin, current regime of the shelf, coastal drainage systems and by the sea/lake water level changes controlled by climate and the sill depths of the two straits, which in turn determined the water exchange between the seas. The sedimentological interpretation of the seismic refl ection profi les and core sediments have allowed us to distinguish fi ve stratigraphic units (S1-S5) and four sedimentary layers (A-D) over the acoustic basement. The lower stratigraphic unit and sedimentary layer are separated from the overlying acoustic basement by a chaotic to parallel and by a high amplitude seismic refl ector. Seaward dipping units of the acoustic basement are inferred to be the seaward continuation of the Oligocene-Upper Miocene units widely exposed on land. The presence of three different marine terraces distinguished (T1-T3) along the northeastern shelf of the Marmara Sea have been associated with the six different curves of the post-glacial sea-level changes. From statistical point of view, the most signifi cant terraces occur from -78 m to -80 m (T1), -58 m to -62 m (T2) and -28 m to -32 m at (T3). Considering the global sea level curves, these terraces can be dated 9.25, 12.25 and 13.75 Cal kyr BP, respectively.

Gaziköy-Mürefte (Marmara Denizi) arasında yer alan sığ denizel bölgenin sismik yansıma verileri ışığında tektonik anlamı, KB Anadolu

“…The upper unit (Unit 1), which deposited during late Quaternary transgression, overlies on units (2 and 3) with an angular unconformity (the green lines on seismic sections). The thickness of the unit indicates some variations on different seismic sections with a range between 30-40 m, which is in accordance with the estimated sedimentation rate of 5 -4 cm/ kyr for northeast of the Sea of Marmara, reported by Ediger et al (2018). Having similar sediment source area characteristics, these two region are also easy to compare with each other, despite the considerable distance between them.…”

Geographic Genetic Structure of Alectoris chukar in Türkiye: Post-LGM-Induced Hybridization and Human-Mediated Contaminations

“…In the post-LGM period, however, the melting of glaciers in the northern latitudes caused a rapid rise in water levels in the Black Sea basin (~13.800 yrBP). The resulting catastrophic water flow from the Black Sea into the Marmara Sea raised the water level of the İstanbul Strait and Marmara Sea [ 147 ]. By ~12.000 yrBP, the rise in global sea levels had caused the present dual flow regime of the Çanakkale Strait, while the same dual flow pattern started at ~5.000 yrBP in the case of the İstanbul Strait [ 145 ].…”