Document Type : Original Research Paper
Authors
1 Associate Professor, Faculty of Earth Sciences, University of Shahrood, Shahrood, Iran
2 Ph.D. Student, Faculty of Earth Sciences, University of Shahrood, Shahrood, Iran
Abstract
Darreh-Bagh granitoidic pluton in the northwest of Aligoodarz composed of two felsic and mafic parts, with lithological composition range from diorite to quartzdiorite, and granodiorite to leucogranite respectively. Felsic rocks have calc-alkaline and peraluminous affinity and belong to S-type and continental arc granitoids (CAG). The most significant characterizes of felsic part are as follows: presence of the metapelitic andalusite bearing enclaves, silica (quartz fragments which inherited from quartz vein with metamorphic origin), surmicaceous and metapasamitic enclaves and also andalusitic xenocrysts through out of the felsic part. Mafic rocks have calc-alkaline and metaluminous affinity and belong to I-type and continental arc granitoids (CAG). Based on the field observations, petrographical and geochemical characterictics, penetration of basic-intermediate magmas into late Triassic - lower Jurassic metapelites and metagraywackes caused to rise temperature up to produce a large scale contact metamorphism including andalusite hornfels and sillimanite hornfels. Intersecting the temperature of melting point of metapelites and metagraywackes resulted in producing melts with suitable composition for forming of S – type granitoid plutons. Then, the produced magma ascended to the higher levels in the upper crust and emplaced in it. Granitoid magmas emplacement are associated with low-extent contact metamorphism up to cordierite hornfels facies.
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