Late quaternary stratigraphic and tectonic evolution of the northeastern Aegean Sea

Isler, Ekrem Bursin (2005) Late quaternary stratigraphic and tectonic evolution of the northeastern Aegean Sea. Masters thesis, Memorial University of Newfoundland.

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Abstract

The late Quaternary-Recent stratigraphic and tectonic evolution of the NE Aegean Sea, between the Islands of Bozcaada and Lesbos and the Biga Peninsula, is examined using ~1600 km of seismic reflection and side scan profiles and six cores collected during cruises in 1998, 2000, 2002, and 2003. -- Detailed examination of the seismic reflection profiles showed that several vertically stacked depositional sequences developed within three NE-SW trending basins. These depositional sequences exhibit oblique- to complex oblique-sigmoid internal seismic reflection configuration and are separated from one another by shelf-crossing unconformities. The chronology of the depositional sequences is constrained by seven radiocarbon and two U/Th dates on in situ shell samples extracted from five cores. Sedimentation rates calculated by using these dates range between 19 cm/kyr and 30 cm/kyr. The ages and the stacked architecture of the depositional sequences, together with the correlations with the oxygen isotopic stages and global sea-level curve reveal that these seaward-prograded delta sequences were developed in a sufficiently rapidly subsiding shelf environment during successive global eustatic sea-level falls associated with late Quaternary glaciations. The progradation of the depositional sequences decelerated and eventually halted shortly after the subsequent major transgressions during which the shelf-crossing unconformities were generated. The terrigenous materials transported throughout the development of the depositional sequences originated from the Tuzla, Karamenderes, and Dümbek rivers draining the Biga Peninsula. -- Seismic reflection profiles showed no evidence for a major E-W-trending fault system, suggesting that the western continuation of the central strand of the North Anatolian Transform Fault does not exit into the Aegean Sea at Ezine. Detailed mapping of the seismic data showed that two major faults, A₁ and β₈, constitute the main fault system in the study area. The Baba Burnu Basin is bounded by these two faults, and is interpreted to develop either as a rhomboidal pull-apart basin or as a half-graben. In the case of being a pull-apart basin, the faults A₁ and β₈ represent the seaward extension of the southern strand of the North Anatolian Transform Fault where it initially runs ~ NW-SE (i.e., fault A₁) and then deflects toward NE-SW (i.e., β₈) forming a releasing bend. It then continues further southwest along fault β₈ and extends as far as the North Skyros Basin. In the case of being a half-graben, the central strand of the North Anatolian Transform Fault continues west in an ENE-WSW direction in the Gulf of Edremit and then it deviates toward southwest off the Island of Lesbos.

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