The recent deep prospecting results in the Jiaojia area of Eastern Shandong Province indicate that the Jiaojia ore field composed of several individual gold deposits as previously suggested is actually an ultra-large ...The recent deep prospecting results in the Jiaojia area of Eastern Shandong Province indicate that the Jiaojia ore field composed of several individual gold deposits as previously suggested is actually an ultra-large gold deposit.This deposit covers an area of ～40 km2,and shows a structural control by the Jiaojia fault and its secondary faults.Gold orebodies generally occur along the same mineralization-alteration belt,and the main orebodies intersect with each other or exhibit a parallel or overlapping distribution.This deposit＇s reserves are estimated to be 1,200t of gold,being the first gold deposit of more than 1000t gold reserves in China.The No.Ⅰ-1 orebody in the Shaling-deep Sizhuang ore blocks holds gold reserves greater than 350 t,or 29 percent of the total reserves,followed by the No.Ⅰ orebody in Matang-Jiaojia ore blocks with exceeding 150t gold reserves.This deposit mainly occurs in the footwall of the Jiaojia fault,and presents zoned patterns in mineralization,alteration and structures.The strongly mineralized zones agree with strongly altered and tectonically fractured zones.These orebodies display strataform-like,veinlike or lenticular shapes,and generally show characteristics of pinching out and reappearing,branching and converging,expanding and shrinking.The orebodies commonly occur along positions where the fault strike changes and in gentle locations with dips changing from steep to gentle.The main orebodies are parallel to the main plane of the orecontrolling fault,and tend to be gentle from the surface to the deep.The orebodies mainly plunge to the southwest,with plunge angle of 45°-606° Orebodies near the main plane of the ore-controlling fault have more gold resource than those away from main fault zone.The slant depth of orebodies is generally larger than the length along its strike direction; orebodies become thick and gold grades become low from the shallow area to the deep area.Ore-forming fluids are H2O-CO2-NaCl±CH4 type with medium-temperature and moderate to low salinity.Sulfur isotopic values （δ34SCDT） for gold ores range between 11.08‰ and 12.58‰,indicating mixed sulfur sources; hydrogen isotopic values （δDVSMOW） range from-83.68‰ to-116.95‰ and oxygen isotopic values （δ18OV-SMOW） range between 12.04‰ and 16.28‰.The hydrogen and oxygen isotopes suggest that ore-forming fluids originated from primary magma,and mixing with a large amount of atmospheric water during the late stage.The Eastern Shandong Province gold deposits are associated with magmatic activities which have mantle crust-mixed source,and also share some similarities with orgenic and epithermal hydrothermal golddeposits.Because Eastern Shandong Province gold deposits with unique metailogenic features and formation setting which are different from other gold deposit types in the world,we call it the Jiaojiatype gold deposits.The kiloton class Jiaojia gold deposit is related to fluid activities,extension and detachment resulted from thermal upweiling of magmas.The strong magmatic activities in the middle to late stage of early Cretaceous in Eastern Shandong Province lead to active fluids,and provided abundant ore-forming materials for gold depsoits.Moreover,many extensional structures resulting from crustal extension provided favourable space for orebody positioning.展开更多
Based on 9 sheets of 1：50,000-scale regional geological survey and guided by the theory of metallogenic systems and integrated analyses of the structural and metallogenic features, this paper hereby puts forward the ...Based on 9 sheets of 1：50,000-scale regional geological survey and guided by the theory of metallogenic systems and integrated analyses of the structural and metallogenic features, this paper hereby puts forward the composite metallogenic systems of the Weihai area, Shandong Province, aiming at solving the problems on the origins and ore-controlling structures of the numerous deposits in the area. Its scientific significance is reflected in the following three aspects： （1） The basic features of the composite metallogenic systems can be recognized, which consist of two types： the Proterozoic metamorphic-hydrothermal metallogenic system and the Mesozoic magmatic-hydrothermal metallogenic system （i.e. the Indosinian-early Yanshanian contact metasomatic metallogenic series and the mid-late Yanshanian magmatic-hydrothermal metallogenic series）. The two series display arcuate and NW-right lateral arrangements and a N-S parallel zonal distribution respectively, with the corresponding mineral assemblages being Au＋Ag＋Pb＋Zn, etc.; and Cu＋Mo＋Fe, Au＋Ag＋Cu＋Pb- Zn＋Mo＋Co-Ni＋sulfides＋silicides＋K-feldspar, etc. （2） The composite metallogenic systems may be used to interpret the complicated genetic relations of the deposits. Through analyses of the relations between the three main metallogenic intervals and their corresponding source rock series （the Jingshan and Rongcheng groups; the Wendong super-unit and the early-middle Yanshanian Weideshan super-unit; and the mid-late Yanshanian Weideshan and Laoshan super-units） as well as a case study of the Fanjiabu gold deposit, we have distinguished the consanguinity between the contact metasomatic （skarn-type） metallogenic series and the magmatic-hydrothermal metallogenic series as well as the noncognate superposition between the two and the metamorphic-hydrothermal metallogenic system. （3） The composite metallogenic systems are easily related to the evolution of continental dynamic regimes. The formation of the metamorphic-hydrothermal metallogenic system has undergone transformations of three different types of tectono-dynamic regimes from extension→compression→ shearing; that of the contact metasomatic （skarn-type） metallogenic system from compression→extension→compression; and that of the magmatic-hydrothermal metallogenic system from extension →subductive compression of the Pacific Plate. The evolutions of the three types are all attributed to the opening-closing or divergence-convergence of the paleocontinent, and all their mineralization corresponds to the interval of transformation from the end of convergence to early integration of the Weihai paleocontinent. All these will benefit our deeper study of the dynamics of continental metallogenic processes.展开更多
Based on our study of the nature and variation of mineralization-controlling faults in their deep extension and the spatial distribution of gold orebodies in the northwestern Shandong Peninsula (NSP), here we propose ...Based on our study of the nature and variation of mineralization-controlling faults in their deep extension and the spatial distribution of gold orebodies in the northwestern Shandong Peninsula (NSP), here we propose that the gold deposits in the Jiaojia gold belt are controlled by listric faults and the gold deposits in the NSP are controlled by extensional fault system. We also suggest that there is a multiple mineralization space in the deep part of the NSP gold belt. As steps or benches occur along the deep extention of the listric fault where its dipping angle changes from steep to gentle, a number of gold deposits are correspondingly distributed as a steplike pattern, which is named as a step metallogenetic model for gold deposits in the NSP. The gold deposits in Shandong Peninsula were formed in the Cretaceous when the crust in the region experienced extention and thinning following the strong collision between North China Plate and Yangtze Plate during the Triassic. Crust anataxis, fluid remobilization, and extention-detachement of the crust are the leading factors for the gold mineralization.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No. 41230311)the National Science and Technology Support Program (Grant No.2011BAB04B09)
文摘The recent deep prospecting results in the Jiaojia area of Eastern Shandong Province indicate that the Jiaojia ore field composed of several individual gold deposits as previously suggested is actually an ultra-large gold deposit.This deposit covers an area of ～40 km2,and shows a structural control by the Jiaojia fault and its secondary faults.Gold orebodies generally occur along the same mineralization-alteration belt,and the main orebodies intersect with each other or exhibit a parallel or overlapping distribution.This deposit＇s reserves are estimated to be 1,200t of gold,being the first gold deposit of more than 1000t gold reserves in China.The No.Ⅰ-1 orebody in the Shaling-deep Sizhuang ore blocks holds gold reserves greater than 350 t,or 29 percent of the total reserves,followed by the No.Ⅰ orebody in Matang-Jiaojia ore blocks with exceeding 150t gold reserves.This deposit mainly occurs in the footwall of the Jiaojia fault,and presents zoned patterns in mineralization,alteration and structures.The strongly mineralized zones agree with strongly altered and tectonically fractured zones.These orebodies display strataform-like,veinlike or lenticular shapes,and generally show characteristics of pinching out and reappearing,branching and converging,expanding and shrinking.The orebodies commonly occur along positions where the fault strike changes and in gentle locations with dips changing from steep to gentle.The main orebodies are parallel to the main plane of the orecontrolling fault,and tend to be gentle from the surface to the deep.The orebodies mainly plunge to the southwest,with plunge angle of 45°-606° Orebodies near the main plane of the ore-controlling fault have more gold resource than those away from main fault zone.The slant depth of orebodies is generally larger than the length along its strike direction; orebodies become thick and gold grades become low from the shallow area to the deep area.Ore-forming fluids are H2O-CO2-NaCl±CH4 type with medium-temperature and moderate to low salinity.Sulfur isotopic values （δ34SCDT） for gold ores range between 11.08‰ and 12.58‰,indicating mixed sulfur sources; hydrogen isotopic values （δDVSMOW） range from-83.68‰ to-116.95‰ and oxygen isotopic values （δ18OV-SMOW） range between 12.04‰ and 16.28‰.The hydrogen and oxygen isotopes suggest that ore-forming fluids originated from primary magma,and mixing with a large amount of atmospheric water during the late stage.The Eastern Shandong Province gold deposits are associated with magmatic activities which have mantle crust-mixed source,and also share some similarities with orgenic and epithermal hydrothermal golddeposits.Because Eastern Shandong Province gold deposits with unique metailogenic features and formation setting which are different from other gold deposit types in the world,we call it the Jiaojiatype gold deposits.The kiloton class Jiaojia gold deposit is related to fluid activities,extension and detachment resulted from thermal upweiling of magmas.The strong magmatic activities in the middle to late stage of early Cretaceous in Eastern Shandong Province lead to active fluids,and provided abundant ore-forming materials for gold depsoits.Moreover,many extensional structures resulting from crustal extension provided favourable space for orebody positioning.
基金the National Natural Science Foundation of China （Grants 40272051 , 40572063） the Key Foundation of National Natural Science in China （Grant 40234051）.
文摘Based on 9 sheets of 1：50,000-scale regional geological survey and guided by the theory of metallogenic systems and integrated analyses of the structural and metallogenic features, this paper hereby puts forward the composite metallogenic systems of the Weihai area, Shandong Province, aiming at solving the problems on the origins and ore-controlling structures of the numerous deposits in the area. Its scientific significance is reflected in the following three aspects： （1） The basic features of the composite metallogenic systems can be recognized, which consist of two types： the Proterozoic metamorphic-hydrothermal metallogenic system and the Mesozoic magmatic-hydrothermal metallogenic system （i.e. the Indosinian-early Yanshanian contact metasomatic metallogenic series and the mid-late Yanshanian magmatic-hydrothermal metallogenic series）. The two series display arcuate and NW-right lateral arrangements and a N-S parallel zonal distribution respectively, with the corresponding mineral assemblages being Au＋Ag＋Pb＋Zn, etc.; and Cu＋Mo＋Fe, Au＋Ag＋Cu＋Pb- Zn＋Mo＋Co-Ni＋sulfides＋silicides＋K-feldspar, etc. （2） The composite metallogenic systems may be used to interpret the complicated genetic relations of the deposits. Through analyses of the relations between the three main metallogenic intervals and their corresponding source rock series （the Jingshan and Rongcheng groups; the Wendong super-unit and the early-middle Yanshanian Weideshan super-unit; and the mid-late Yanshanian Weideshan and Laoshan super-units） as well as a case study of the Fanjiabu gold deposit, we have distinguished the consanguinity between the contact metasomatic （skarn-type） metallogenic series and the magmatic-hydrothermal metallogenic series as well as the noncognate superposition between the two and the metamorphic-hydrothermal metallogenic system. （3） The composite metallogenic systems are easily related to the evolution of continental dynamic regimes. The formation of the metamorphic-hydrothermal metallogenic system has undergone transformations of three different types of tectono-dynamic regimes from extension→compression→ shearing; that of the contact metasomatic （skarn-type） metallogenic system from compression→extension→compression; and that of the magmatic-hydrothermal metallogenic system from extension →subductive compression of the Pacific Plate. The evolutions of the three types are all attributed to the opening-closing or divergence-convergence of the paleocontinent, and all their mineralization corresponds to the interval of transformation from the end of convergence to early integration of the Weihai paleocontinent. All these will benefit our deeper study of the dynamics of continental metallogenic processes.
文摘Based on our study of the nature and variation of mineralization-controlling faults in their deep extension and the spatial distribution of gold orebodies in the northwestern Shandong Peninsula (NSP), here we propose that the gold deposits in the Jiaojia gold belt are controlled by listric faults and the gold deposits in the NSP are controlled by extensional fault system. We also suggest that there is a multiple mineralization space in the deep part of the NSP gold belt. As steps or benches occur along the deep extention of the listric fault where its dipping angle changes from steep to gentle, a number of gold deposits are correspondingly distributed as a steplike pattern, which is named as a step metallogenetic model for gold deposits in the NSP. The gold deposits in Shandong Peninsula were formed in the Cretaceous when the crust in the region experienced extention and thinning following the strong collision between North China Plate and Yangtze Plate during the Triassic. Crust anataxis, fluid remobilization, and extention-detachement of the crust are the leading factors for the gold mineralization.
