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    甘肃阳山超大型卡林-类卡林型复合式金矿床特征

    Characteristics of the superlarge Yangshan Carlin and Carlin-like compound type gold deposit in Gansu

    • 摘要: 提要:阳山金矿于世纪之交勘查并扩大为超大微细浸染型金矿,矿床形成受地层、浅成花岗斑岩、韧-脆性剪切构造及热液活动的多种因素的叠加与改造控制,研究认为矿床具有卡林型和类卡林型两种矿化类型特点,卡林型矿化于韧性剪切早、早—中期阶段和晚期阶段,分别出现含砷黄铁矿-毒砂-次显微金-白云石-石英矿化组合及黄铁矿-辉锑矿-石英方解石矿化组合,及Au-As-Sb-Hg的成矿地球化学组合;类卡林型矿化出现在脆性中—晚期阶段,以黄铁矿-毒砂-自然金-碲铋矿-白云石-石英矿化(含黄铜-闪锌-方铅矿)组合为特征,及Au-As-Cu-Pb-Zn-Te-Bi成矿地球化学组合。阳山复合式金矿含矿地层中沉积成岩黄铁矿δ34S为-24.6‰~-29.0‰,早期—早中期韧-脆性剪切金属硫化物矿化产物δ34S值为5.0‰~7.0‰,中—晚期蚀变花岗斑岩中金属硫化物矿化产物δ34S值为-2.9‰~-2.1‰,显示地层中生物硫、强变形造山带地壳硫、少量岩浆硫混入的多源特征。流体包裹体氢氧同位素与硫同位素近同步特征,成矿热液显示地下流体、强烈改造水和少量岩浆水的混合。

       

      Abstract: Abstract:The Yangshan gold deposit is a very finely disseminated gold deposit, which was explored at the turn of the century and expanded into a superlarge deposit. The deposit was controlled by superposition and modification of many factors such as strata, hypabyssal granite-porphyry, brittle-ductile shear and hydrothermal activities. The gold deposit has the characteristics of both Carlin type and Carlin-like type mineralization. The Carlin-type mineralization occurred during the early, early-middle and late stages of ductile shearing, when there appeared the As-bearing pyrite-arsenopyrite-submicroscopic gold-dolomite-quartz assemblage and pyrite-stibnite-quartz-calcite assemblage, as well as the Au-As-Sb-Hg geochemical assemblage. The Carlin-like type mineralization took place during the middle-late stage of brittle shearing, which is characterized by the pyrite-arsenopyrite-native gold-tellurobismuthite-submicroscopic gold-dolomite-quartz assemblage (with chalcopyrite, chalcopyrite and chalcopyrite) and the Au-As-Cu-Pb-Zn-Te-Bi geochemical assemblage. The δ34S values are -24.6‰ to -29.0‰ for sedimentary diagenetic pyrite in ore-bearing strata of the gold deposit, 5.0 to 7.0‰ for the metal sulfide formed during the early and early-middle stage of brittle-ductile shearing and -2.9 to -2.1‰ for the metal sulfide in altered granite porphyry of the middle-late mineralization stage, suggesting the multi-source features of mixing with biogenic sulfur in strata, crustal sulfur in strongly deformed orogenic belts and a little magmatic sulfur. The hydrogen and oxygen isotopes in fluid inclusions show nearly sympathetic variations with δ34S, and hydrothermal ore fluids are the mixture of underground fluids, strongly modified meteoric water and a little magmatic water.

       

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