Narigongma porphery molybdenite copper deposit,northern extension of Yulong copper belt:evidence from the age of Re-Os isotope.

Narigongma molybdenite copper deposit locates at the south Qinghai province,which is the northern segment of Sanjiang in southwest China and is bounded to the north by the Jinshajiang sature and to the south by the Bangonghu-Nujiang sature.This area is a tectonic transfer belt,which absorbs and accommodates the stress and strain coming from the collision of India and Asia continents. Affected by this collision,the tectonic deformation in this area is very complicated.Since 51 Ma,series of NW-SE trending thrust faults and strike-slip faults are formed,companying with potassic magma simultaneously.Narigongma porphyry molybdenite copper deposit is formed in Cenozoic biotite granite porphyry and its boundary with wall rocks.For absence of reliable aging data,the occurrence environment of the deposit is not known by people,and the relationship with Yulong porphyry copper deposit belt is blurry,6 samples of molybdenite are taken from Narigongma molybdenite copper deposit to analyze for Re-Os isotope dating,yielding a Re-Os isochrone age of 40.86±0.85Ma (MSWD=0.79).This age is consistent with the mineralization age of the Yulong porphyry,and Narigongma should be the northern prolongation of Yulong copper belt.Large extension of metallogenic belt indicates that there is still a tremendous potential of finding a large porphyry copper (molybdenite) deposit in the region from Yulong to Narigongma.