An Example for Arc-Type Granitoids Along Collisional Zones: The Pertek Granitoid, Taurus Orogenic Belt, Turkey

Abstract

The Pertek granitoid consisting dominantly of diorite, quartz diorite, quartz monzodiorite, tonalite and lesser granite, adamellite and syenite, is considered to form the easternmost continuation of the Central Anatolian Crystalline Complex. Diorite and monzonites of this granitoid complex are cut by the granitic dykes. The Pertek granitoid, in the study area, is found in the Permo-Triassic Keban metamorphic sequence along intrusive and tectonic contacts. Along the intrusive contacts metasomatic mineralizations are common. Granitoids are, depending on the mineralogical composition, low-, middle- high-K subalkaline features. Major oxide-SiO₂ variation diagrams show that fractionation (particularly plagioclase, hornblend, pyroxene and olivine fractionation) played an important role on the granitoid formation during a continuous crystallization process. Distribution of the samples from the Pertek granitoid in the tectonic setting diagrams, and their chondrite- and primordial mantle-normalized trace element patterns resemble to the of arc-type granitoids. Trace element and rare earth element compositions indicate that the magma, from which the Pertek granitoid crystallized, derived from a mantle that was enriched by the fluids derived from the subducted slab, however this magma was contaminated by the crust during its intrusion. These geochemical characteristics are also supported by the field observations. The field and geochemical characteristics of the Pertek Granitiod suggest that they are similar to the other granitoids cropping out in the central and eastern Anatolia and they form the lateral continuation of the same magmatic belt.