Geological characteristics of the Pulang porphyry copper deposit, Yunnan
FAN Yu-hua, LI Wen-chang (Yunnan Institute of Geological Survey, Dali 671000, Yunnan, China)
The Pulang porphyry copper deposit is located on the eastern margin of the Dege-Zhongdian block on the western side of the Garze-Litang junction zone, in the southern segment of the Indosinian Yidun-Zhongdian island-arc belt. The strata of the copper district are the Upper Triassic Tumugou Formation, and there mainly outcrops the Indosinian Pulang composite intermediate-acid porphyry. Structural fissures are well developed and rocks are strongly altered, showing typical "porphyry type" alteration zoning with intense silicic alteration zone→silicic-potassic alteration zone→phyllic alteration zone→propylitic alteration zone from the center outward. Magmatic rocks, strata emplaced by magma, hydrothermal alteration and structural space for hy-drothermal fluid transport and deposition of ore substances controlled the occurrence of this deposit. The mineralization occurred in the Pulang composite porphyry and mineralization and alteration occur in company. A pipe-shaped orebody composed of veinlet-disseminated ores formed in the center of the intrusion and vein -shaped orebodies formed at edges of the intrusion. The dominant ore element of the deposit is copper, with many subordinate useful components such as gold, silver, molybdenum, palladium and sulfur. The deposit reaches the superlarge size.