Re–Os Isotopic Dating of the Molybdenite from the Tongshan Porphyry Cu–Mo Deposit in Heilongjiang Province, NE China

Strata outcropped in Tongshan area is mainly composed of the Middle Ordovician Tongshan Fm. and Duobaoshan Fm. The Ordovician granodiorite intrusions spread widely. The NW–trending reversed S–shaped structures control the occurrence of alteration and mineralization. Four ore bodies have been identified in the deposit. No. III ore body, also in the footwall of the Tongshan fault, is the largest and the major ore body in the area, with 1140 m in length, more than 800 m along the dip. Metallic minerals account for 3–7% of the minerals in the ore, primarily pyrite and chalcopyrite, with some molybdenite, bornite, galena, sphalerite, etc.. Wall–rock alteration is well developed in the Tongshan deposit, and from southwest to northeast are successively potassium–silicification zone, sericite–silicification zone and propylitization zone. The data mentioned in this paper and previous studies (Zhao et al., 1997, 2011; Wu et al., 2009) demonstrate that the Tongshan is a porphyry Cu–Mo deposit. 2 Molybdenite Re–Os Isotopic Analysis