Petrology and contact metamorphism of Salafchegan quartz diorite intrusion

Abstract

The circular Salafchegan quartz diorite intrusion (Aleh Mountain) has intruded into the sandy limestone and sandstone of the Upper Red Formation of Upper Miocene age. It is a concordant pluton and has slightly metamorphosed country rocks. This body is composed of quartz diorite and could be divided into a layered structures outer part and a massively outcropped central part. These rocks show geochemical calc-alkaline affinity. They could be classified as meta-aluminous, similar to I type granitoids. These rocks are enriched in LILE (Large Ion Lithophile Elements) and LREE (Light Rare Earth Elements) but depleted in HREE (High Rare Earth Elements). In addition, they show negative anomalies of Nb and Ti, with a high Al content. Based on petrographic studies and geochemical analysis, it could be suggested that the parent magma of these rocks was related to a subduction zone and has emplaced in a magmatic arc. The contact aureole of the intrusion is indicated by the existence of minerals such as garnet, epidote, wollastonite and scapolite. The mineral assemblage in the contact aureole is demonstrated that albite-epidote-hornfels facies grade of metamorphism took place to the hornblende hornfels facies.