Discovery of sharang large-scale porphyry molybdenum deposit, the first Single Mo deposit in Tibet and its significance

Abstrct：Recently, series of major breakthroughs for porphyry copper exploration have been made in the Gangdese Metallogenic belt in Tibet. Alteration and mineralization ages of the Gangdese porphyry-skarn Cu(Mo) deposits concentrate in the range of 30～12 Ma, formed in the extension environment of late stage of collision between India and the Asian continents or the transitional environment from the post-collisional compression setting to strike-slip extension. However, the independent porphyry molybdenum deposit associated with the collisional setting has not been reported so far. This paper studies the ore-bearing porphyries, the types and horizational and vertical zonation of hydrothermal alteration, the characteristics of hydrothermal vein system and mineralization, according to the systmatic fieldwork and the mapping work of the drilling holes. The granitic porphyry is the ore-forming intrusion with intensive alteration of 9 km2 in area. It concludes that, Sharang porphyry molybdenum is single porphyry molybdenum without any other important accompanying metal resources and it has been formed in the main collisional setting around 55 Ma. This study compares the scale of alteration and the intensity of mineralization with the same type of molybdenum deposits. Based on the comparisons and the results of TEM and induced electrical survey, the Sharang porphyry molybdenum deposit has rather large vertical extension to 800 m in the depth and showes excellent metallogenic conditions and great potential for further exploration. The establishment of the Sharang single porphyry molybdenum deposit will enrich the metallogenic pedigree of the giant Gangdese porphyry metallogenic belt. This discovery has a great significance for regional research and prospecting.