Mesoscopic Tectonic Features of the Marmara Island and the Kapıdağı Peninsula, NW Turkey

Authors: Rahmi AKSOY

Abstract: Pre-Permian metamorphites formed in various environments and Alpine granitoidic rocks are found in the Marmara Island and the Kapıdağı Peninsula. Metamorphic rocks have undergone progressive regional metamorphism under medium pressure/medium-high temperature (MPMHT) conditions and four phases of deformation by Caledonian (?) orogeny. These are, in sequence, (1) schistosity and foliation planes, (2) overturned or recumbent, isoclinical-close folds, mineral and crenulation lineations, crenulation cleavages and mullion structures, (3) isoclinical-close or similar folds, mineral and crenulation lineations, crenulation cleavages and mullion structures and (4) gentle-parallel folds, crenulation cleavages and lineations. In the study area the metamorphism and accompanying deformations came to a close with the uplift of the region before Permian. Calcalkaline magmatism occured during the Alphine orogeny and sub-sequently Ocaklar and Çeltikçi granitoids were emplaced in the region. In the north of the Kapıdağı Peninsula the Ocaklar granitoids deformed by a shear zone that trends approximately east-west. This shear zone developed by an intra-orogenic strain. It is observed that the region has been affected by active subsidence and uplifting today.

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