The Geological Characteristics And Genesis Research Of Liuxianzhuang Gold Deposit,Zhaoyuan,Shandong Province

Liuxianzhuang gold deposit lies in Zhaoyuan city of Shandong province,to the east of the collisional structural belt between the North China and Yangtze plates,the Yishu fault belt.It is a large gold deposit controlled by the Zhaoping metallogenic zone.The regional basement rock series belongs to the Jiaotong stratigraphic microregion of the East Shandong subregion of the North China stratigraphic region.It mainly includes the Mesoarchean Tangjiazhuang rock group,Neoarchean Jiaodong rock group,Paleoproterozoic Jingshan and Fenzishan groups,and Mesozoic Cretaceous and Cenozoic Quaternary formations.Within the area,structures are quite well developed.By characteristics,they are either ductile or brittle deformation structures.Brittle fault structures are the most widely present and they have a close connection with metallogenesis.The well developed and widespread magmatic rocks,spanning from Mesoarchean to Mesozoic Yanshanian in age,include the late Mesoarchean Guangdiwa?Ar₂G?and Shibapan?Ar₂s??sequences,Neoarchean Wutaian–Fupingian Malianzhuang?Ar₃M?,Qixia?Ar₃Q?and Tangezhuang?Ar₃Tg?sequences,Paleoproterozoic Daliuhang?HtD?and Laizhou?HtL?sequences,Mesozoic Yanshanian Linglong?J₃L?and Duogushan?J₂D?sequences,and derivative vein rocks of the Linglong-Zhaofengding dike zone.The orebodies,controlled by the Zhaoping main trunk fault belt and located in the downthrow of the main fault plane of the Zhaoping fault belt,close to the main fault plane,are hosted in the beresitized granitic cataclastic belt.Orebody I-1,which belongs to the same orebody as the Daobeizhuangzi main orebody in the neighboring area,sits between exploratory lines No.17 and No.33,in the elevation interval of-470m^-1492 m.The orebody is distributed as stratiform beds or large veins and characterizes branching–recombination,expansion-shrinkage,and pitched distribution.It has the same attitude as the main fault plane,strikes 20°⁶7°with an average strike of 45°and dips SE with a dip angle ranging from 34°to 52°and an average dip angle of 45°?as confined by exploratory line No.32,the dip angle of the orebody changes to 52°between 32ZK2 and 32ZKX1?.The ore-forming fluids for the Liuxianzhuang gold deposit have been confirmed to have low salinity?0.88²2.44 wt%NaCleqv?and low density?0.62¹.08 g/cm³?.The ore-forming temperature was mostly 103³00°C;the ore-forming pressure interval was 92.58²67.12 MPa;the ore-forming depth was 6.84¹2.65 km.Metallogenesis took place in the late Yanshanian.Hydrogen and oxygen isotopic compositions indicated that the projection point of the Liuxianzhuang?Daobeizhuangzi?gold deposit obviously falls below magmatic water and metamorphic water,between magmatic water and rainwater.The?¹⁸O results demonstrated a close connection with magmatic water.The directional deflection of the atmospheric precipitation line highlighted a level of contribution of atmospheric precipitation to the metallogenic process.The ore-forming fluids,consequently,appear to have come from both magmatic water and atmospheric precipitation.Sulfur isotopic analysis suggested that the sulfur must have been a mixture of both mantle-and crust-derived sulfur instead of either of them alone.The ore-forming material probably came from the Linglong granite and the Jiaodong rock group.Based on all characteristics discussed above,we suggest that the Liuxianzhuang gold deposit is genetically a medium-temperature hydrothermal vein type gold deposit.