Rockforming and Oreforming Ages of the Yaogangxian Tungsten Deposit of Hunan Province

The Yaogangxian tungsten deposit of Hunan province is located in the central part of the Nanling EW-direction tectonic belt, interjunction of Caledonian uplift zone and Indosinian-Yanshanian hollow zone. The strata of Cambrian, Devonian, Carboniferous and Jurassic widely spread in the area with Cambrian and Devonian as the dominant ore-bearing strata. The ore body hosted in the inside and outside contact zone of the early Yanshanian granite. On the basis of geological structure, rock geochemistry, isotope chronology and other research of the deposit, the authors used SHRIMP U-Pb, Rb-Sr and Re-Os isochrone techniques to determine the ages of rockforming and oreforming in the Yaogangxian mine. The Yaogangxian granite mass and wolframite-quartz vein which hosted in inside and outside of mass contact zone was tested and the SHRIMP U-Pb age, of (170.7±2.2) Ma (95% confidence, n=12，MSWD=1.7) was obtained and the age of (175.8±4.1) Ma (95% confidence, MSWD=0.88) for the wolframitequartz vein which located in outside of mass contact zone and the age of (156±3) Ma (95% confidence, MSWD=0.20) for the wolframitequartz vein which located in inside of mass contact zone were also obtained. While the Re-Os isochron age for molybdenite was (170±5) Ma (MSWD=0.34). The results indicate the formation of the Yaogangxian tungsten deposit undergoing at least two mineralization periods, corresponding to J1/J2 and J2/J3 transition periods respectively. Furthermore, the rock-forming and ore-orming process of the deposit is featured by multi-stage and multi-phase superimposing, and the process of ore-forming is coupling with the process of rock-forming.