Molybdenite Re-Os Dating and its Geological Implication for the East Gebi Molybdenum deposit of the Eastern Tianshan Mountain in Xinjiang

The East Gebi Molybdenum deposit located between the Kangguer fracture and Yamansu fracture in the east of Hami Kumudage sand ridge,east Tanshan mountain,Xinjiang province.The ore-body is in the top of concealed porphyritic potassium feldspar granite rock,the characteristics of the surrounding rocks are metamorphism argillaceous sandstones,metamorphism sandy mudstones and metamorphic sandstones of early Carboniferous Gandun group.The ore minerals are mainly Molybdenite,Pyrite and little Chalcopyrite,Rutile,Galena,Sphalerite,Scheelite,Ilmenite and so on,the Molybdenite occurred in Quzrtz-veins and cracks formed the oreshoot.The Re-Os isotopic of the Molybdenite shows that the isochron age of the deposit is(231.1±1.5) Ma and the weighted average age is(232.3±1.2) Ma,the deposit was formed in mid-Triassic.The age of the deposit shows that a peak mineralization occurred at Indosinian in east Tianshan mountain region.This study gives some new evidences and clues for rebuilding the magmatic evolution and the mineralization since Mesozoic in east Tianshan mountain region.