Genetic Mineralogy Of Pyrite And Fluid Inclusion Characteristics Of Quartz In Canzhuang Deposit,Zhaoyuan City,Shandong Province

Canzhuang gold mine, a typical altered rock type gold deposit，is located in thenorth of the Jiaojia gold-deposit belt of Jiaodong Peninsular. Shangzhuang goldmining area is the important gold deposit of Canzhuang. The deposit occurs in thecontacting zone of the Linglong granite and the Guojialing granodiorite, controlled bythe wangershan fault which is the branch of Jiaojia fault.The wall rock alteration of Shangzhuang gold mining area is developed, such asK-feldspar, reddening, phyllic alteration, Silicide al. In the process of alteration,themain components which enter in are Au、Ag、 As、Hg、Bi、SiO₂、FeO、K₂O、MgO etc. The process of alteration is alonging with mineralization of gold.The analysis of pyrite’s trace elements reveals that mineralization of gold is relatewith magmatic hydrothermal activity. The analysis of REE reveals thatore-forming fluid source is probably relate with Guojialing granodiorite andJiaodong Group metamorphic rocks. The thermoelectric coefficient of pyrite rangesfrom-346.1μν/℃to342.7μν/℃, with the conduction type mixed of P type and Ntype, but N type is far more than P type. Thermoelectric coefficient is mainlynegative value, account82.6%, positive value account17.4%. The resistivity of pyriteis about0.05²76.38·cm, with an average of18.48·cm.The research of the fluid inclusions in quartz reveal that the homogeneoustemperature of I stage ranging from260～340℃. Ⅱ～Ⅲ stages is mainly from200to290℃. The salinity ranges from3.0～14.97%, and the mean value is8.6%.The density ranges from0.782to1.018g/cm3, and the mean value is0.867g/cm3.The ore-forming fluid belongs to low-salinity and density fluid system. The capturepressure of fluid inclusions from20.2to201MPa. The ore-forming depths is about4.7km, so it is a deep hydrothermal ore deposit.The gas component of fluid inclusions is dominated by H2O and CO2, and alsohave little H₂、N₂、CO、CH₄etc. The positive ions of influid inclusions are mainlyCa²⁺and Na⁺, Secondly are K+and Mg2+;and the main negative ions are Cl-and SO₄^2-,Secondly are F-and NO-. The ore-forming fluid belongs to low-salinityH₂O-CO₂-NaCl gas-liquid system.Estimating oxygen fugacity of the ore-forming fluid which is lgfO2=-10.81～-13.81, mean value is-11.77. The value is decreased from the former ore–forming to the later ore–forming. The value of PH is4.70～6.19, and the mean value is5.11,indicating that the ore-forming fluid is Weak acid–acid fluid. The value of Eh isrange from﹣0.93～﹣0.23（mean value is-0.44）, revealing that the ore-forming fluidis reductive fluid.The research of H-O isotope reveals that the former stage of ore-forming fluid ismagmatic water and the later stage is atmospheric water of Canzhuang gold deposite.At last, the ore-forming fluid had evolved a mixed fluid of magmatic water andatmospheric water.The fluid medium have a dramatic change due to the changes of the ore-forming stress field, which lead to the immiscibility of the fluid. CO₂has exsolutionedand causes siliceous matter and pyrite especially the gold deposited.