2012•Dadi gouzao yu chengkuangxueRequires access
~(40)Ar-~(39)Ar Dating of Sericite in the Nongruri Gold Deposit of Tibet and its Geological Significance
Liu Bo
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Abstract
The Nongruri gold deposit is located in Gangdise-Himalaya metallogenic belt,southern Qinghai-Tibet plateau.The mineralization was strictly controlled by the SN fault.The Nongruri gold deposit is the first epithermal Au deposit discovered in the Gangdese metallogenic belt.The ore-forming age of the Nongruri gold deposit is still in dispute.In order to obtain the ore-forming age,the authors measured the sericites separated from the altered granite-porphyry which hosts the gold deposit.The 39 Ar-40 Ar analyses yield weighted average age and isochron age of(19.87±0.96) Ma and(19.70±0.30) Ma,respectively.It is held that the Au mineralization in the Nongruri deposit took place in Miocene,which is consistent with the ore-forming epoch of the porphyry copper ore deposits in the adjacent regions.This suggests that the Nongruri epithermal Au deposit,the skarn polymetallic copper deposits,and the porphyry copper ore deposits were formed in the same magma—fluid mineralization system controlled by an extensional dynamic setting in the Gangdise belt.