Writers : Rastad.E, Tajeddin. H.A , Rashid Nezhad Omran.N and Baba Khani.A.R
Refference : Geosciences Scientific Quarterly Journal,No.:35-36,P.:60
Publishing Year : 1380

Abstract :
Darestan- Baghu gold mining area is exposed at about 100 km south of Damghan. The area is a part of Torud- Chahshirin volcano-plutonic belt that crops out as a horst with a NE-SW trend in the northern limit Dasht-e-Kavir. The outcrops in the area are Middle Eocene volcano- pyroclastics with andesite to dacite in composition, which are intruded by a number of intrusives including granite to granodiorite bodies.
Mineralization in Darestan gold occurrence consists of a copper (gold)- bearing silicic vein with 400 meter length occurring within a N-S trending normal fault in andesitic to dacitic- andesitic massive breccia tuff associated with silicic, argillic and propylitic alterations. Mineralization in the vein includes quartz, chalcopyrite, pyrite, gold, specularite, malachite, and iron- hydroxides.
Gold minerlization in Baghu vein (at about 3 km NE of Darestan gold occurrence) is as a silicic vein with 700 meter length occurring within a granodiorite- granite subvolcanic with argillic alteration. Mineralization in Baghu vein consists of quartz. pyrite. chalcopyrite. gold. iron oxides and iron- hydroxides, malachite, chalcocite, covellite and tourmaline.
Field observations indicate that considerable contents of gold in Darestan area mainly related to sulfide- bearing silicic veins are intruded within N-S normal faults that are generally associated with hydrothemal alteration of argillic. silicic and chloritic (±epidote) zones. Investigation on other mineralized zones of Darestan and Baghu areas suggests a clear genetic relationship between Darestan copper (gold) occurrence and gold-bearing silicic vein of Baghu.
Field observations and laboratory studies show a close relationship between the copper (gold) mineralization and late- stage silicic solutions induced from subvolcanic intrusives with acidic to intermediate composition in Darestan and Baghu districts. Some of the most important lines of evidence are spatial relationship between ore-bearing silicic veins and the position of subvolcanic intrusives, in addition high correlation between Au and Cu and homogenization temperatures of primary fluid inclusions improve genetic relationship.
Subject List : Genesis