The types and prospects of the gold deposits in eastern Xizang

The eastern Xizang area is an important part of nonferrous and precious metallogenic zone, and a highly deformed area during the Cenozoic in the central and northern parts of the Nujiang-Lancangjiang-Jinshajiang area, where the gold and silver deposits are preferentially hosted. A lot of the gold deposits in eastern Xizang have been recognized, including sedimentary (gold placer), sedimentary-diagenetic, volcanic, porphyry-type, fractured filling-metasomatic, qartz-vein and porphyry copper-associated gold deposits, of which the porphyry-type and fractured filling-metasomatic are most common. The parent rocks of the porphyry-type gold deposits consist of the Cenozoic partially alkaline porphyries. The orebodies occur generally in porphyries, cryptoexplosion breccias, contact zones and outer contact-alteration zones. The main ore-forming elements are composed of gold, silver, lead, zinc, copper and tungsten. The latter orebodies appear commonly in the secondary faults, derived faults, interformational fractured zones and joint and cleavage development zones close to the regional rifts. The main ore-forming elements consist of gold, silver, lead, zinc, copper, antimony and mercury. The mineralization ages are represented by the Cenozoic and Cretaceous-Cenozoic times. The present paper deals also with the division of the tectonic elements and Cenozoic partially alkaline rock belts in eastern Xizang, with the emphasis on the mineralization, source rocks, alteration, geochemical anomaly, indicators and prospects of the two types of gold deposits cited above.