Petrographic and geochemical studies of intrusive rocks,Around of Khanbaz village, northwest of Meshkinshahr

Category Petrology
Group GSI.IR
Location 21th symposium on geosciences
Holding Date 21 May 2008

      The granitoides of northwest of Meshkinshahr are located in zone of west Alborz-Azarbaijan with age of Oligocene. These rocks are intruded into volcanic rocks with age of Eocene. On the base of petrography studies and modal classification, the composition of this complex belongs to granite, monzonite, quartz-monzonite, monzo-diorite and quartz-monzo-diorite. We can see hydrothermal alteration in north part of study area considerably that has effected on granitoides and volcanic rocks a lot, and lead to changes in rocks minerals such as alteration of plagioclase to serisite, orthoclase to clay minerals (kaolin), hornblende and biotite to chlorite and calcite and also the alteration of augite to uralite. Presence of two kind of separate feldspar and also presence of watery minerals like biotite and amphibole that are because of high pressure of fluid phase, indicates that these granitoides are subsolvus. There are some dykes with micro-granite, monzonite and doleritic composition in plutonic mass that are effected alteration. Geochemical studies indicate that these rocks are located at high potassium and shoshonitic series. The rocks of this complex belong to met-aluminous series in aspect of aluminum saturate index. Mineralogy and geochemical studies and using different diagrams indicate active continental margin and post collision for tectonic setting and I type granites for these rocks.