Re-Os dating of molybdenite from the Yaguila porphyry molybdenum deposit in Gongbo'gyamda area, Tibet, and its geological significance

Located in the Gongbo'gyamda County of Tibet, the Yaguila Pb-Zn, Mo deposit is a porphyry Mo skarn-hydrothermal vein type deposit occurring in the eastern part of the Gangdise belt. For the purpose of finding out the mineralization time of the porphyry type molybdenum deposit in the Nianqingtanggula mineralization belt, the authors selected five molybdenite samples from the Yaguila ore district to perform the Re-Os dating. The Re-Os dating yielded weighted average model ages of (64.27±0.9) to (65.97±1.13) Ma, varying in a narrow range, and an isochrone age of 65.0±1.9Ma(MSWD=3.2). It is proved that the porphyry type molybdenum deposit of the Yaguila ore district was formed during Early Eocene. The results indicate that there occurred large scale ore-forming processes during the main Indian-Asian collision period in the Gangdise belt.