Petrogenesis of the Yaogangxian granites and implications for W mineralization Hunan Province

The Yaogangxian composite granitic pluton is located in the north of Nanling complex structural belt,hosting the giant Yaogangxian tungsten deposit. The Yaogangxian granites are differentiation S-type granite with the characters of highlyacid,hyperalkaline and peraluminous,belonging to the high-K calc-alkalic series granite. LA-ICP-MS zircon U-Pb dating method was applied to obtain the ages of different types of the Yaogangxian granites. The Yaogangxian composite granitic pluton can be divided into three stages according to their emplacement ages,including coarse-grained two-mica granite forming at 170 Ma,medium-to fine-grained two-mica granite forming at 162 Ma,and fine-grained muscovite granite forming at 157 Ma,indicating that the granitic magma had undergone multi-epoch pulsating emplacement. The element geochemistry and Sr-Nd isopotic characters show that source materials of the Yaogangxian granites might come from pelite in the Paleoproterozoic Era. The Yaogangxian granites formed at 170 Ma to 157 Ma belonging to the Yanshannian Period,occurring in a continental crustal extension and thinning setting. The diagenetic events of the Yaogangxian granites and the metallogenetic events of tungsten deposits were highly consistent in time and space. The granitic magma had experienced high fractional crystallization and produced volatile-rich fluid. So it was indicated that the granites may provide original fluid and material source to mineralization in post-magmatic hydrothermal stage.