Zhunuo Cu-Mo-(Au) deposit, Ngamring Co. (Angren Co.), Xigazê Prefecture (Rikaze Prefecture; Shigatse Prefecture), Tibet, Chinai

Regional Level Types
Zhunuo Cu-Mo-(Au) deposit	Deposit
Ngamring Co. (Angren Co.)	County
Xigazê Prefecture (Rikaze Prefecture; Shigatse Prefecture)	Prefecture
Tibet	Autonomous Region
China	Country

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Porphyry Cu-Mo-(Au) deposit, hosted by granitoid porphyry in the core of a 3 x 4 km sized polyphasal intrusive complex.

The Zhunuo deposit (2.37 Mt of Cu at 0.57%) is located near Angren, 200 km west of Xigaze, in the western Gangdese belt.
Three major quartz vein types have been identified at Zhunuo according to vein mineral assemblages and geometric features, quartz textures, and crosscutting relationships. The A, B, and D veins to describe the three vein types at Zhunuo. A veins contain anhedral to subhedral, granular quartz crystals, are discontinuous and up to 2-cm thick, and have diffuse to sharp contacts with the host rocks. In addition to quartz, A veins typically contain pink K-feldspar, biotite, and minor anhydrite, chalcopyrite, bornite, and pyrite. B veins contain subhedral to euhedral quartz crystals that are oriented perpendicular to straight vein walls, and typically lack alteration halos. These veins are typically planar, continuous, and have sharp contacts with the wall rocks, with thicknesses ranging from 2 mm to 5 cm. The characteristic center lines in typical B veins are not always well developed at Zhunuo. In addition to quartz, B veins contain molybdenite, chalcopyrite, pyrite, and minor tourmaline. D veins consist mainly of muscovite, quartz, and pyrite and are generally associated with phyllic alteration, marking a waning stage of the magmatic-hydrothermal system. These veins are typically continuous, straight, and planar with sharp contacts with the wall rocks, and are 2 to 20 mm thick. Orebodies are generally centered on the monzogranite porphyry and the adjacent monzogranite. Chalcopyrite and bornite are the major Cu-Fe sulfides at Zhunuo. Economic quantities of Au and Mo are not present at Zhunuo. Only a few grains of molybdenite were found as small flakes within the quartz B veins.

The giant Zhunuo porphyry deposit is located in the west part of the Gangdese belt in southern Xizang, containing 2.9 million tons of (Mt) Cu with an average grade of 0.48%. C veins were irregular and mainly composed of minerals such as chalcopyrite and chalcopyrite. Orebodies in the Zhunuo deposit occurred with an irregular lens shape and were developed within the monzogranite porphyry. Spatially, orebodies developed within the potassic alteration zone and were overprinted by the phyllic alteration. Chalcopyrite and bornite dominated the economic Cu-Fe sulfides in this deposit. Molybdenite mostly occurred as flaky or scaly aggregates distributed in the B veins. Pyrite was also widely distributed in this deposit, especially within the D veins. Overall, the Cu grade had a positive correlation with the abundance of A and B veins. A decreasing trend of Cu grade with distance could be observed from the center of the monzogranite porphyry.

Notably, neither potassic alteration nor propylitic alteration alone is associated with significant Cu mineralization. Instead, Cu precipitation is preferentially developed in potassic-altered rocks (e.g., Miocene monzogranite and monzogranite porphyry) that were subsequently overprinted by later phyllic alteration.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

18 valid minerals.

Rock Types Recorded