Fan HR,Hu FF,Yang JH,Shen K and Zhai MG.2005.Fluid evolution and large-scale gold metallogeny during Mesozoic tectonic transition in the eastern Shandong province.

The Jiaodong Peninsula or eastern Shandong gold province,the most important gold producer in China,is located in the southeastern margin of the North China craton.The gold deposits in the Jiaodong are divided into three gold belts,respectively Zhaoyuan-Laizhou-Pingdu,Penglai-Qixia and Muping-Rushan from west to east.They occur as gold-bearing quartz veins and disseminated- and stockwork-style ores adjacent to fault zones.Most of the gold deposits comprise a quartz-K-feldspar,quartz-pyrite quartz-base metal sulfide,and quartz-carbonate paragenetic sequence.Obtained Ar-Ar,Rb-Sr isochron ages and hydrothermal zircon SHRIMP U-Pb age dating give gold mineralization time at 120±10Ma.The Sr,Nd isotopic compositions of pyrites and the associates rocks suggest that the ore-forming materials were probably derived from a mixed source.Fluid inclusion studies show that ore-forming fluids of gold deposits are consistent in the whole Jiaodong Peninsula with similar mineralizing temperature and pressure conditions.The fluids are characterized by H_2O-CO_2-NaCl±CH_4.The best mineralizing temperature and pressure are 170～335℃ and 70～25℃ MPa.Oxygen and hydrogen isotope data show that metamorphic fluid contribution is minimal and that ore fluids are of magmatic origin. Gold deposits in the Jiaodong Peninsula are formed in the same mineralizing-geodynamic circumstance,and related with Mesozoic tectonic transition in the eastern China.Gold metallogeny is one of expression form of Mesozoic tectonic transition.