ZARMITAN GRANITOID-HOSTED GOLD DEPOSIT, TIAN SHAN BELT, UZBEKISTAN

摘要

The 10-Moz Zarmitan gold deposit is located in the Nuratau region in central Uzbekistan. This area represents a part of the late Paleozoic Tian Shan orogenic belt. The belt formed as a result of a late Paleozoic orogenic collision between the Tarim-Karakum continent and the Kazakhstan-north Tian Shan plate and represents one of the richest gold provinces in the world. The Zarmitan deposit, containing 84 major orebodies and numerous smaller veins, is partially hosted by the Koshrabad granitoid intrusion, the geochemical characteristics of which indicate a late orogenic affinity. The gold-bearing veins are distributed as a complex anastomosing east-west-striking and concave to the north swarm. The strike length of this zone is approximately 7 km, and the thickness varies from 200 to 1,500 m. The total resource of the 84 major lodes is 32 million tonnes (Mt) at 9.8 g/t Au and 14.6 g/t Ag. Gold mineralization is associated with reverse vertical movement accompanied by left-lateral strike-slip displacement along high-angle faults, which represent splays off the Karaulkhana-Charmitan fault zone. This fault is one of the major structures in the Northern Nuratau area and is a major control on mineralization along the southern contact of the Koshrabad pluton, including the Zarmitan deposit. The highest gold grades and highest Au/Ag ratios are found in gold-bearing veins from the central part of the Zarmitan deposit, which is also characterized by abundant hydraulic breccias. This study considers new field and mine data from Zarmitan with earlier studies of the deposit and with recent models for intrusion-related gold deposits.