A Study On The Geology And Metallogenic Model Of Lingqueshan Gold Deposit In Zhaoyuan, Shandong Province

The Lingqueshan gold deposit is located at the place 25km south to Zhaoyuan City, in the hanging wall of the Zhao-Ye gold zone,one of the three major gold mineralization zones in Jiaodong. The deposit occurs mainly in the Jiaodong rock group. The ores are mainly of the auriferous quartz vein type hosted in NE trending fractures and faults. Wall-rock alterations are most potassic alteration, siliconization,quartz-sericitization, pyritization and carbonatization.According to research of geological characteristica of deposit and analysis of fluid inclusion of quartz sulphide veins ore and calculation of pressure,it is considered that Lingqueshan gold deposit belongs to mesother-mal deposit. Its metallogenic temperature is 250 - 340℃,and pressure is 30 -102Mpa,metallogenic depth is 1 - 3.7Km.Sulfur isotope analyses show that 6 34S values of pyrites vary in the range of 6.6‰~10.4‰, with an average of 7.9‰. Pb isotope analyses reveal that 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb rations of the ore lead are 17.114~ 17.774,15.451 ~ 15.566,36.917~38.737, respectiv -ely,which are significantly different from the data of granites.The research results suggest that the Lingqueshan gold deposit might have partly derived its ore-forming materials from the mantle,and that it shares similar geochemical characteristics with the other gold deposits in the Zhao-Ye gold zone. Which have the same material origin and genetic modelThe δ18O value of the the quartz vein ranges from 11.89% to 14.03%,andthe average value isl2.99%.The 5Dh2O values of inclusion fluid vary from -94.12% to -101.13%, and the average value is -98.07%. According to the H-0 isotopes fractionation equation between quartz and water,proposed by clayton,the 818O of ore-forming water an equilibrium state ranges in 2.30%-2.37%, It is founin in the 8Dh2o518O-D18O H20S diagram that the ore-forming fluid is projected no atmospheric water and magma water, which indicates that the ore-forming fluid is a mixed hydrothermal fluid of atmospheric water and magmatic waterThe Rb-Sr isochron dating methods were adopted to date deposite, the result indicate that the age of the Lingqueshan gold deposite is 117±7Ma. It is consistency with the age of jiaodong gold deplsites concentration zone (120+ lOMa). That is to say, the large-scale metallogeny of the Zhao-Ping fault zone hanging wall took place in early cretaceous occurred in north western Jiaodong Peninsula.Metallogensis of the Lingqueshan gold deposit in Shandong Province has been a question under dispute for a long time. There are many points such as metamorphic hydrothermal, magamatic hydrothermal and meteoric water. Detailed study shows that mantle-rooted fluids were involved in the ore-forming processes. Evidence for this argumentation comes from: (I) discordogenic fault;(II) intersecting and accompanying of basic veins and lodes;(III) geochemistry of stable isotopes;(IV) geochemistry of fluid inclusions;and (V)mufti-level circulation and exchanging of mantle-rooted fluids. Based on the characteristics of the circulation system of mantle-rootedfluids and its close relation to magmatic hydrothermal fluids and meteoric water, ore-bearing fluids are divided into three subsystems: (I)C-H-O-rich fluid circulation subsystem in mantle;(II) Si-richfluid circulation subsystem in the middle and lower crust;and;(EH) S-rich fluid circulation subsystemin shallow and surface crust. Ore-forming functions of these subsystems are controlled respectively by their different geodynamic settings.