Southern Menderes Massif: an incipient metamorphic core complex in western Anatolia, Turkey

Abstract

In the southern sector of the Menderes Massif, north of Selimiye (Milas) augen gneisses interpreted as a deformed peraluminous granite have been dynamothermally metamorphosed and are surrounded by and intrude a regionally metamorphosed Palaeozoic ‘envelope’. The granitic rocks exhibit a moderately-dipping mylonitic foliation and NNE-SSW- trending mineral elongation lineation. The progressive deformation of the granitic rocks produces a structural sequence typical of an extensional shear zone marked, from bottom to top, by a very thick extensive zone of mylonites followed in turn by brecciated mylonite and cataclasite. The kinematic indicators exhibit a top-to-the south, down-dip sense of shear. These structures are attributed to exhumation of the granitic rocks of the massif along a major, south-dipping, normal-sense shear zone that accommodated crustal extension during Late Oligocene collapse of the orogen in western Turkey. Thus, the southern Menderes Massif may be interpreted as the exhumed footwall of a major extensional shear zone, and possibly as an incipient core complex.