GEOCHEMICAL AND PETROLOGICAL FEATURES OF THE PRECAMBRIAN METAMAFIC ROCKS IN MUTKI (BITLIS MASSIF) AREA, SE-TURKEY

The metamafic rocks are represented by amphibolite, garnet-bearing amphibolite and amphibole-bearing schists, associated with a series of supracrustal metasediments in Pan-African basement of the Bitlis massif. The geochemical data of the samples propose different igneous protolithes varying from calcalkaline basalt to andezite. The samples can be classified as Group-1(low Zr) and Group-2 (high Zr), all displaying various enrichments in large ion lithophile (LIL) and light rare earth (LRE) elements and depletion in high field strength (HFS) elements. High LILE/HFSE and LREE/HREE ratios, a variety of tectonomagmatic diagrams offer clearly a destructive plate margin geotectonic setting for the samples. The metamafic rocks are suggested to have formed mostly by fractional crystallization of plagioclase, apatite and titaniferous magnetite +/- olivine +/- clinopyroxene +/- amphibole; coupled with minor crustal contamination in relation with subduction-related magmatism neighboring the Andean-type active margins of Gondwana. The samples were then regionally metamorphosed at amphibolite facies conditions, between 540-610 degrees C at similar to 5 kb.