Stratigraphic Evolution and Tectonics in an Area of High Seismicity: Akyazı/Adapazarı (Pontides, Northwestern Turkey)

Authors: Emil GREBER

Abstract: In the western Keremali Mountains (southernmost İstanbul zone), the crystalline basement is overlaid by Upper Cretaceous to probably Miocene sediments and volcanic rocks. The complex geological situation is to some extent due to paleo-Alpine (Late Cretaceous-Paleocene) syn-sedimentary tectonics. Typical features are locally restricted occurrences of lithologies, rapid lateral and vertical changes in the stratigraphic columns, neighbouring zones of erosion and accumulation and the predominance of coarse clastic sediments. This paleo-Alpine phase was followed by the main-Alpine phase (Early Eocene) which is related to the juxtaposition of the Istanbul and Sakarya zone and the consumption of the Intra-Pontide Ocean. This phase is associated with a regional uplift combined with a tilting and slight folding of the strata and widespread volcanism in the study area. Relicts of the Intra-Pontide Ocean in form of serpentinite lenses are exposed in the southernmost study area (Civek Zone). The Neo-Alpine (Miocene-present) North Anatolian Fault zone overprinted the whole study area and reactivated the Intra-Pontide suture as a right-lateral fault zone.

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