Vol.2 – 1996 – No.2 – Journal of the Black Sea / Mediterranean Environment

LARGER OSTRACODA IN THE SEA OF MARMARA: GENERAL DISTRIBUTION OF BOSQUETINA DENTATA (G.W. MULLER, 1894)

Larger ostracoda in the sea of Marmara: general distribution of Bosquetina dentata (G.W. Muller, 1894)

Cemal Tunoğlu

Hacettepe University, Geological Engin. Dept. 06532, Beytepe, Ankara, TURKEY

Abstract

Bosquetina dentata (G.W.Müller, 1894) is a benthic ostracoda specimen which has larger dimensions than the other ostracoda species of the Sea of Marmara. This species is known very common in all around of the Mediterranean. B. dentata are found and observed generally shallow-circolittoral but fairly deep-marine in the sea of Marmara.

Keywords: Ostracoda, Bosquetina dentata, sea of Marmara, recent, Turkey

General Distribution of Pterigocythereis jonesii (Baird, 1850) and Pterigocythereis ceratoptera (Bosquet, 1852) (Ostracoda) in the sea of Marmara

General distribution of Pterigocythereis jonesii (Baird, 1850) and Pterigocythereis ceratoptera (Bosquet, 1852) (Ostracoda) in the sea of Marmara

Cemal Tunoğlu

Hacettepe University, Geological Engineering Departmen,. 06532 Beytepe, Ankara, TURKEY

Abstract

Genus Pterigocythereis and related species are known all around of the Mediterranean recently. Pterigocythereis jonesii and P. ceratoptera are important species which they observed for the first time with this study in the benthic ostracoda thanatocoenosis and biocoenosis of the Sea of Marmara. These species have been found in all of the locations of shallow water at depths between 20-60 m. and especially in near-shore throughout the Sea of Marmara coasts. Their habitat are exist different types of substrate, but they prefer commonly on sandy mud and silty mud bottom sediments.

Keywords: Ostracoda, Pterigocythereis, Sea of Marmara

EXTENTS OF THE NORTH ANATOLIAN FAULT IN THE YZMIT, GEMLIK, AND BANDIRMA BAYS

Extents of the North Anatolian Fault in the Izmit, Gemlik, and Bandırma Bays

Aykut Barka, Ismail Kusçu

ITU, Faculty of Mining Department of Geology, Ayazağa, Istanbul, TURKEY
MTA, Ankara, TURKEY

Abstract

High resolution shallow seismic reflection profiles, surveyed by MTA Sismik-1 in the Izmit, Gemlik and Bandmna bays, in 1984, were re-examined in order to understand geometry and kinematics of the northern and middle strands of the North Anatolian Fault. We used the pull-apart model to detect the course of the strands. We concluded that this approach fits well with the fault patterns and all three strands seems to have identical fault geometry and kinematics. GPS measurements geomorphology, bathimetry and tickness of sediment in the basins, and historical earthquake records in the eastern Marmara Sea region show that slip rate is higher along the northern strand than the middle strand suggesting higher earthquake risk along the northern strand of the North Anatolian Fault.

Keyword: Shallow seismic reflection profiles, lzmit, Gemlik and Bandırma Bays

Late quarternary depositional environments on the outhern Marmara shelf

Late quarternary depositional environments on the southern Marmara shelf

Mustafa Ergin, Nizamettin Kazancı, Baki Varol, Özden Ileri, Levent Karadenizli

Ankara University, Faculty of Sciences, Department of Geological Engineering, Tandoğan, 06100 Ankara, TURKEY

Abstract

In this study, 182 surficial sediment samples have been used to investigate the characteristics of sedimentary depositional environments on the southern Marmara shelf. Grain size analyses revealed the presence of, at least, three distinct depositional zones where sediments contained relatively high sand and gravel components partly derived from the remains of benthic organisms. Zone 1 extends from the Bozburun Peninsula in the east to the west off Imralı Island in the west. Zone 2 extends from the east off Marmara Island to the east off Kapıdağ Peninsula. Zone 3 extends from west of Marmara Island towards southwest. The sediments of these three zones grade into fine-grained mud both in nearshore and offshore directions. The presence of ridge-like and high bottom reliefs, based on bathymetric profiles, further suggest that these zones could be relict features such as former shorelines resulted from the last sea-level changes. Due to lack of data, possible influences of neotectonics remain questionable. Zone 3 seems to be controlled by a complex of mechanisms. Further investigations are underway.

Keywords: Sediment, southern Marmara shelf, carbonat contents, grain size

DISTRIBUTION OF CARBONATE AND ORGANIC CARBON CONTENTS IN LATE QUATERNARY SEDIMENTS OF THE SOUTHERN MARMARA SHELF

Distribution of carbonate and organic carbon contents in late quaternary sediments of the southern Marmara shelf

M. Namık Çağatay, Oya Algan, Nuray Balkıs, Mehmet Balkıs

Institute of Marine Sciences and Management, University of Istanbul, Istanbul, TURKEY

Abstract

A total of 165 surface and 81 core samples from four gravity cores were analyzed for their total carbonate and organic carbon contents. The sediments are generally low in carbonate content (<10% CaCO₃) along the inner shelf. Relatively higher values (>10% CaCO₃) are found on the outer shelf to the north, along a belt extending from the Bozburun Peninsula to west of Mamara Island. Patches of >20% CaCO₃values occur between the lmralı Island and Bozburun Peninsula, NE of the Kapıdağ Peninsula, and in a belt extending west from the Kapıdağ Peninsula, through the Avşa Island to Karabiga. The high carbonate areas generally correspond to the sandy sediments with high contents of shell material. Total organic carbon content of the surface sediments ranges from 0.10-2.50%, with the high values being located in shallow areas along the coast and decreasing values occuring in the offshore direction. This distribution pattern suggests that the organic-carbon matter is mainly of terrestrial origin. Depth profiles of organic carbon values along the core samples indicate the presence of a sapropel layer in two cores (No.22 and 13) in the Gemlik Gulf. The highest carbonate (8-12% CaCO₃) and organic carbon values (1.7-2.11%) are found in a phosphorescent green, plastic, clayey sapropelic mud horizon at a depth ranging from 1. 75 to 2. 15 m. This layer is enriched in planktonic foraminifera but depleted in benthic foraminifera species, suggesting both the high surface organic productivity and bottom unoxic conditions. It was probably deposited following the Holocene transgression during a pluival period when increased quantities of nutrients were supplied by rivers into the Sea of Marmara and when water stratification was established. Radiometric carbon, organic and isotope geochemical studies are in progress on this layer.

Keywords: Sea of Marmara, quaternary sediments, sapropels, organic carbon, total carbonate