New mineralogic data on the metamorphism of the Alanya nappes, Demirtaş-Alanya, Central Taurus, Turkey [Demirtaş-Alanya yöresinde Alanya naplarinin metamorfizmasina ilişkin yeni mineralojik bulgular, Orta Toroslar, Türkiye]

Abstract

The Alanya Metamorphics cropping out in the Demirtaş-Alanya area consist of Mahmutlar (Permian and Pre-Permian), Sugözü and Yumruda? (Permian-Triassic) nappes from bottom to top. Mahmutlar Nappe shows a progressive evolution as; 2M1 sericitic mica, llb chlorite (clinochlore), 2M1 white K-mica and 1M biotite related to increasing metamorphism from upper (phyllite, metasiltstone) to lower part (biotite schist and garnet-mica schist). Ideal muscovite-phengitic white K-micas have bo values that are characterized by a facies series of the medium pressure to upper part of the low pressure metamorphism. Sugözü Nappe is made up garnet-mica schist including metabasite (eclogite, glaucophane schist) interbands and/or lenses. The crystallinity and bO values of phengitic micas in the metapelites, including phyllosilicates such as muscovite, ripidolitic llb chlorite, rarely paragonite, illitesmectite and smectite, represent epizone and medium pressure facies conditions, respectively. The Yumruda? Nappe is characterized by its bearing the index and/or indicator minerals such as chloritoid and paragonite, trace amounts of 1 Tc pyrophyllite, kaolinite/dickite and margarite, and have similar composition with Bolkarda? and Alada? units of the northern part of the Taurus Belt. Epimetamorphic 2M1 K-micas and llb chlorites have compositions of ideal muscovite-phengite and ripidolite, respectively. bo values of K-micas indicate a facies series of low pressure to lower part of medium pressure metamorphism. The nappes exhibit different lithologies and metamorphic features. The Sugözü Nappe displaying an earlier high pressure/low temperature metamorphism has been overprinted together with the structurally overlying Mahmutlar Nappe by a later Barrowian-type metamorphism. The Yumruda? Nappe, on the other hand, is characterized by a metamorphic evolution with a typical anticlockwise P-T-t path, indicating that its emplacement on the other nappes is relatively late. The formations of crenulation fold and cleavage, mylonitic texture together with the crystallization of chloritoid, ripidolitic chlorite, chlorite-smectite, chlorite-vermiculite and illite-smectite in the Yumruda? Nappe is assumed to be due to this later nappe-movement.