Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Genesis and gold (Copper) potential in Darestan-Baghu mining area (South of Damghan)

Document Type : Original Research Paper

Authors
Ebrahim Rastad 1
Hossein Ali Tajeddin 2
Nematollah Rashid Nezhad Omran 1
Alireza Babakhani 2
1 Department of Geology, Tarbiat Modarres University, Tehran, Iran
2 Geological Survey of Iran, Tehran, Iran
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 meters 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 mineralization 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 hydrothermal 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.
Keywords
Gold
Hydrothermal alteration
Subvolcanic intrusives
Fluid inclusions
South of Damghan
Iran

Subjects

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Scientific Quarterly Journal of Geosciences
Volume 9, 35-36
Spring & Summer 2000, Vol. 9, No. 35-36
Autumn 2000
Pages 60-79