中国含金夕卡岩矿床的分布和主要地质特征

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夕卡岩金矿床主要分布于中国东部,特别是在长江中下游地区,并常和夕卡岩铜(铁或多金属)矿床共生。它们产生的有利构造环境为地台边缘的拗陷和褶皱带以及地台内部的深大断裂附近地区。主要控矿地层为石炭-二叠纪和三叠纪碳酸盐岩。有关侵入岩为钙-碱性闪长岩、石英闪长岩、石英二长闪长岩、花岗闪长岩、二长花岗岩及其浅成相,大多属燕山期。含金夕卡岩以钙夕卡岩为主,镁夕卡岩次之。在夕卡岩及其邻近的围岩中叠加有较强的退化热液蚀变,并常伴有Cu、Au、Fe、Mo、Pb、Zn、Ag等矿化,显示明显的交代分带。总的矿化分带序列为:Fe(Cu)→Cu(Mo)→Cu、Au→Au→Au、Pb、Zn。在许多矿床中,发现有碲化物、铋化物和硒化物。因此,Cu、Au、Te、As、Bi、Pb、Zn、Ag、Se等元素在夕卡岩金矿床中相对富集,并成为重要的地球化学找矿标志 The Skarn gold deposits are mainly distributed in the eastern part of China, especially in the middle and lower reaches of the Yangtze River, and often coexist with the skarn copper (iron or polymetallic) deposits. The favorable tectonic setting they produce is the depression and fold belt along the edge of the platform and the area near the deep faults within the platform. The main ore-controlling strata are Carboniferous-Permian and Triassic carbonate rocks. The intrusive rocks are calc-alkaline diorite, quartz diorite, quartz diorite, granodiorite, monzonitic granite and their shallow facies, mostly Yanshanian. The gold skarn is dominated by calcium skarn, followed by the magnesium skarn. Degraded hydrothermal alteration in skarn and its adjacent wall rocks is accompanied by mineralization such as Cu, Au, Fe, Mo, Pb, Zn and Ag, showing obvious alternation zoning. The total mineralization zoning sequence is: Fe (Cu) → Cu (Mo) → Cu, Au → Au → Au, Pb, Zn. In many deposits, tellurides, bismuth and selenides are found. Therefore, Cu, Au, Te, As, Bi, Pb, Zn, Ag, Se and other elements are relatively enriched in the skarn gold deposit and become an important geochemical prospecting indicator
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