Writers : Ketabi, P.; Mohammadi, S.; Zarin Koob, M. H.
Refference : 28th Symposium on Geosciences and the 14th Symposium on Geological Society of Iran
Publishing Year : 1389

Abstract :

The study area is located in southwest of Birjand , in southeast of Sheikh Abad village. This region has covered with paleogene and Neogene volcanic and subvolcanic rocks. These rocks have different composition and include Pyroxcene Andesite, Dacite and Diorite porphyry. Based on petrographic studies, XRD and XRF analysis on samples altered, kaolinitisation, silicification and alunitisation have occurred which is important for gold, silver and mercury mineralization in this region. porphyritc texture with glass groundmass is dominant in these volcanic rocks. The main phenocrysts are plagioclase, amphibole, biotite and clinopyroxene, and quartz and opaque minerals are in less amount. Plagioclase alteration to clay and calcium carbonate is pervasive. Silica, kaolinite, jarosite and natroalunite are the common minerals in alteration zone in these volcanic rocks. Based on Fe + Ti / Cr + Nb ratio in kaolinite samples, these minerals can be hipogene type.

Subject List : mineralography