Writers : Yari, fatemeh; Mohammadi ,Seyyed saeid; Zarrinkoub, Mohammad hossein
Refference : 2nd National Symposium of Iranian Society of Economic Geology
Publishing Year : 1390

Abstract :

The study area is located in southeast of Birjand, SouthKhorasan province and in the northern part of Sistan suture zone. Based on petrography, volcanic rocks include of andesite to andesitic basalt and Pyroclastic rocks are tuff, bricca, and agglomerate. Volcanic and pyroclastic rocks are of the main units that crroped after ophiolitic mélange units in the south of Birjand. Existence of large volumes of acid to intermediate volcanic activity in the Southeast of Birjand in Tertiary, caused suitable conditions for bentonite genesis. Alteration of tuffs in the border of Harivand village, formed bentonite. Geochemical studies (XRF) indicated that Harivand bentonite is Ca- bentonite. On the basis of mineralogical studies (XRD), montmorillonite, albite, Cristobalite, quartz are common minerals. Due to the low percentage of montmorillonite, Hrivand bentonite is not suitable for casting.

Subject List : volcanic rocks