Plio-Quaternary Sandy Deposits and Microbial Buildups at the Southern Marmara Shelf Near Shoreface Area, Turkey

• Main Authors: Denizhan Vardar, Hande Aykurt Vardar
• Format: Article
• Language: English
• Published: IJEGEO 2014-11-01
• Series: International Journal of Environment and Geoinformatics
• Subjects: Sandy deposits; microbial buildups; seismic profiles; bioherm structures; Southern Marmara Shelf
• Online Access: http://dergipark.gov.tr/download/article-file/287078

Understanding the formation and evolution mechanism of the sandy deposits plays key role to define the hydrodynamics of the shelves and coasts. The barrier islands determined from high resolution chirp seismic reflection profiles, were started to deposit on the boundary (SB) that characterized by the lowstand stages of global sea level in the southern Marmara shelf near shoreface area. The unit haslost its activity at 55 ms, 60 ms depth in Erdek Bay, at 55 ms in Bandırma Bay, at 61 ms front of the Kocasu River. According to global sea level curves, this unit was evolved between 11000-11500 BP and10450-10150 BP. The geometrical situation and internal reflection character of these units indicate the balance between fluvial sediment transportation, marine intrusion and current systems in the study area. Belkis Isthmus that connects the Kapıdağ Peninsula to the mainland occurred synchronously with same process that formed the barrier islands. Bioherm structures were formed on the barrier islands and some of the bioherm’s uppermost surface is reached to 1 m below the sea floor. Bioherm structures are composing from organisms; formation and evolution depend on various stress factors. Barrier islands provide nutritional source to bioherms. Since these structures occur in a limited area, the development should be controlled by secondary factors. Biogenic gas determined from seismic sections closed to bioherm structures, probably plays the secondary role. Addition to this, during the forming and the growing of bioherms, Marmara Islands (Pasalimanı, Avşa, Marmara Islands) and Imralı Island were possibly control the currents and the flooding in the study area and provided convenient environment to these structures evolution.