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甘肃文县地区阳山超大微细浸染型金矿床的成因与类型
Genesis and types of the Yangshan superlarge micro-disseminated gold deposit,Wenxian,Gansu,China
【摘要】 含矿岩石为本区泥盆系的一套Au含量较高的炭-硅-泥质地层。其中发现大量含As异常(含As约0.15%)的草莓状黄铁矿;矿体沿断裂带呈构造透镜体-扁豆体斜列等间距分布,产于断裂带中次级破碎带或顺层剪切带内;在早—中期阶段的矿化硫化物中,金以不可见金赋存于含As黄铁矿及毒砂中,含As黄铁矿发育增生环带,载金矿物主要沿片理化带呈微细浸染状分布;在中—晚期阶段的金属硫化物-石英碎裂脉体中,可见显微颗粒金;斜长花岗斑岩为地壳重熔型花岗岩,具多期次性;H、O、S同位素及流体包裹体资料表明,成矿流体以大气降水为主,岩浆水也参与成矿。由此可见,阳山金矿具沉积-岩浆叠加-构造及热液改造的多因复成特征,矿床属超大型卡林-类卡林复合型金矿床。
【Abstract】 The ore-bearing rocks in the Yangshan gold deposit, Wenxian, Gansu, are a sequence of Devonian carbonaceous-siliceous-argillaceous sediments, which contains abundant framboidal pyrite with As anomaly (~0.15% As). Orebodies occur as tectonic lenses or pods equidistantly along the secondary fractured zone or bedding-parallel shear zone in a fault belt. In mineralized sulfide in the early-middle phase, Au occurs as invisible gold in As-bearing pyrite and arsenopyrite. As-bearing pyrite displays overgrowth zoning. The Au carriers mainly occur as micro-disseminations along the schistose zone. Microscopic gold grains are visible in metal sulfide-quartz crushed veins formed in the middle and late phases. Plagiogranite porphyry is crustal anatectic granite formed by multiple intrusions. H, O, and S isotope and fluid inclusion data indicate that ore fluids consist mainly of meteoric water mixed with small amount of magmatic water. Thus it follows that the Yangshan gold deposit is a superlarge Carlin and Carlin-like type polygenetic gold deposit with magma-telescoped, sedimentary and tectonically and hydrothermally modified features.
【Key words】 Carlin and Carlin-like type polygenetic gold deposit; Yangshan gold deposit; South Qinling;
- 【文献出处】 地质通报 ,Geological Bulletin of China , 编辑部邮箱 ,2006年11期
- 【分类号】P618.51
- 【被引频次】56
- 【下载频次】369