摘要
西秦岭成矿带下古生界的赋矿地层分布于南带,主要为志留系,次为寒武系;而上古生界的赋矿地层在南带和北带均有分布,主要为泥盆系,次为石炭系—二叠系.其中,寒武系主要赋存后生浅成中-低温热液作用有关金矿(伴生铜、铀、钼、锑、硒等).志留系赋存同生沉积作用有关钼钒(伴生镍、铀)、磷、石煤、锰和灰岩矿,后生浅成中-低温热液作用有关金、银、锑、汞和铀矿(伴生铜、钼、镍、钒),局部有表生风化淋滤作用有关褐铁矿、铀矿.南带泥盆系赋存同生沉积作用有关煤、白云岩、石膏、铁和磷矿,后生浅成中-低温热液作用有关铁、金、汞和硫铁矿,局部有表生风化淋滤作用有关褐铁矿;北带泥盆系赋存喷流沉积-改造作用有关铅锌矿及铜矿,后生浅成中-低温热液作用有关铁、铜、金、锑和汞矿,局部有表生风化作用有关白铅矿-菱锌矿.南带石炭系—二叠系赋存沉积作用有关灰岩、白云岩,后生浅成中-低温热液作用有关金和汞矿.北带石炭系—二叠系赋存火山沉积-改造作用有关铅锌矿,后生浅成中-低温热液作用有关金和锑矿等.此外,在西秦岭向东昆仑过渡地带,石炭系—二叠系赋存有火山沉积-改造作用有关铜和锡矿.总之,地层控矿基本分两类:①含矿(同生及准同生关系),矿体是地层的组成部分,成矿时代同于含矿地层时代(志留纪、泥盆纪、石炭纪、二叠纪).②容矿(后生及表生风化关系),矿体不是地层的组成部分,成矿时代明显晚于容矿地层的时代,区内后生浅成中-低温热液作用主要发生在中生代,风化作用主要发生在新生代.沉积-改造型矿床可视为两种控矿类型的叠加.容矿地层是否矿源层,需具体情况具体分析.
Abstract
The lower Paleozoic ore-bearing strata in the western Qinling metallogenic belt are mainly distribut-ed in the southern belt,predominantly consisting of the Silurian system and followed by the Cambrian system;The upper Paleozoic ore-bearing strata are distributed in both the southern and northern belts,primarily com-posed of the Devonian system,followed by the Carboniferous-Permian system.Among them,the Cambrian sys-tem mainly occurs gold deposits(associated copper,uranium,molybdenum,antimony,selenium,etc.)related to epigenetic hypabyssal medium-low temperature hydrothermal function.The Silurian system occurs molybde-num,vanadium(associated with nickel and uranium),phosphorus,stone coal,manganese and limestone miner-als related to syngenetic sedimentation function,epigenetic hypabyssal medium-low temperature hydrothermal function in the formation of gold,silver,antimony,mercury and uranium(associated copper,molybdenum,nick-el,vanadium),the local has limonite and uranium deposits related to supergene weathering leaching function.The Devonian system in the southern belt occurs coal,dolomite,gypsum,iron,and phosphate deposits related to syngenetic sedimentation function,epigenetic hypabyssal medium-low temperature hydrothermal function in the formation of iron,gold,mercury,and pyrite,the local has limonite related to supergene weathering leaching function.The Devonian system in the northern belt occurs lead-zinc and copper deposits related to Jet sedimen-tation-transformation function,epigenetic hypabyssal medium-low temperature hydrothermal function in the for-mation of iron,copper,gold,antimony,and mercury deposits,the local has cerussite and smithsonite related to supergene weathering function.The Carboniferous-Permian system in the southern belt occurs limestone and dolomite deposits related to sedimentation function,epigenetic hypabyssal medium-low temperature hydrother-mal function in the formation of gold and mercury deposits.The Carboniferous-Permian system in the northern belt occurs lead-zinc deposits related to volcanic sedimentary-transform function,epigenetic hypabyssal medium-low temperature hydrothermal function in the formation of gold and antimony deposits.Additionally,in the tran-sitional belt from the west Qinling to the east Kunlun,the Carboniferous-Permian system occurs copper and tin deposits related to volcanic sedimentation-transform function.In summary,the ore control by strata in the area can be classified into two categories:①ore-bearing deposits(syngenetic and quasi-syngenetic relationship),the ore body is an integral part of a stratum,where the mineralization occurred during the same period as the forma-tion of the ore-bearing strata(Silurian,Devonian,Carboniferous,and Permian).②ore-hosting deposits(epige-netic and supergene weathering relationship),the ore body is not part of the formation,where the mineralization occurred significantly later than the formation of the ore-hosting strata,epigenetic medium-low temperature hy-drothermal function primarily occurred during the Mesozoic era,while weathering function mainly occurred dur-ing the Cenozoic era.Sedimentary-transformation type ore deposits can be considered as the overlapping of these two types of ore controls.The identification of whether the ore-hosting strata act as ore source layer de-pends on specific geological circumstances and requires further analysis.
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