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Seismic stratigraphy of Late Quaternary sediments of western Mersin Bay shelf, (NE Mediterranean Sea) |
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| Authors: | Mahmut Okyar Mustafa Ergin Graham Evans |
| Institution: | aInstitute of Marine Sciences, Middle East Technical University, Erdemli, Mersin, 33731 Turkey bGeological Research Center for Fluvial, Lacustrine and Marine Environments, Faculty of Engineering, Ankara University, Tando?an, Ankara, 06100 Turkey cDepartment of Geology, Royal School of Mines, Imperial College, London SW7 2BP, England dDepartment of Oceanography, University of Southampton, Southampton SO9 5NH, England |
| Abstract: | High-resolution shallow seismic-reflection profiles obtained from the western Mersin Bay have revealed the existence of the two distinct depositional sequences (C and B) lying on a narrow and relatively steeply-sloping continental shelf which mainly receives its sediments from the ephemeral rivers. The upper Holocene sedimentary sequence (C) is characterized by stratified (simple to complex) to chaotic reflection configurations produced by the development of a prograding wedge of terrigenous sediment. Particular occurrences of slope- and front-fill facies and the lack of a sharp boundary, which has, however, been observed on the western shelf of this bay, between the Early Holocene and latest Pleistocene deposits are related to possible movement of underlying deposits due to local gravity mass movements or synsedimentary tectonics due to adjustment of the underlying evaporites in adjacent basin. The maximum thickness of the topmost sequence C is associated with the Tarsus–Seyhan delta, which lies to the northeast of the area and is prograding along the shelf. Other variations in thickness (5–40 m) of this topmost sequence are related to the variable sediment discharge along the coast, and the distance from the coast. It is at a maximum (40 m) in the nearshore area just west of the Lamas river mouth and at a minimum (5–15 m) in the offshore area. The lower depositional pre-Holocene sequence (B) is characterized by continuous to wavy reflection configurations and how some cyclicity, suggesting coarse, heterogeneous sediments deposited under high energy conditions (fan-deltas) of Plio-Pleistocene age. The combined interpretation of seismic reflection profiles with the available bore-hole data reveals the existence of a widespread Miocene acoustic basement (A) off the Susano?lu–T?rtar coasts and Karap?nar–Gilindirez rivers mouths. Unusual features in some profiles suggest the escape of coastal freshwater into the accumulating sediment. |
| Keywords: | Holocene Late-Quaternary shallow seismic depositional sequence Cilicia Basin Mersin Bay |
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