Zircon U-Pb Dating of Ore-Bearing Rocks and Molybdenite Re-Os Age in Shapinggou Porphyry Molybdenum deposit,Anhui Province

The Shapinggou deposit occurred in the Dabie metallogenic belt is a superlarge porphyry molybdenum deposit discovered in recent years.Based on the analysis for the mineralization feature of the deposit,zircon LA-ICP-MS U-Pb ages were determined for the ore-bearing rocks in Shapingguo deposit.Zircon U-Pb dating yields ages of(122.51±0.81)Ma,(121.5±1.3)Ma and(120.7±1.1)Ma for fine-grained quartz syenite,medium-grained quartz syenite and syenite porphyry,respectively.The187Re and187Os contents of molybdenite from the molybdenum deposit are determined by the Inductively Coupled Plasma Mass Spectrometry(ICP-MS).The Re-Os model ages of the molybdenite samples vary from(100±1.8)Ma to(113.6±1.7) Ma.The time difference between magmatism and mineralization of the Shapingguo deposit was about 7 Ma,which implicated there long active history of the ore fluid in the deposit.The long activities of the ore fluid in the deposit may be a key condition of being a superlarge molybdenum deposit.The ore-forming age of the Shapingguo deposit is identical to the age of porphyry molybdenum mineralization in the Dabie metallogenic belt,which in the later molybdenum mineralization period in the East Qinglin Mountains.The molybdenum deposits occurred in Dabie Mountains are a main part of the East Qinglin-Dabie metallogenic belt.The porphyry molybdenum deposits in the East Qinglin belt and in the Dabie belt are products of syntectonic-magmatic activity,which shared similar settings of metallogenic dynamics.