發(fā)布時(shí)間：2018-05-01 06:29

  本文選題：礦床地質(zhì) + 硫和鉛同位素　； 參考：《地質(zhì)學(xué)報(bào)》2017年06期

【摘要】：納雍枝鉛鋅礦床位于揚(yáng)子陸塊西南緣,是黔西北地區(qū)五指山背斜內(nèi)近年來(lái)取得勘查突破的大型鉛鋅礦床(1.30Mt),也是川滇黔礦集區(qū)貴州境內(nèi)目前發(fā)現(xiàn)的最大規(guī)模的鉛鋅礦床。礦體受層位和構(gòu)造控制明顯,呈似層狀、脈狀及透鏡狀產(chǎn)于五指山背斜南東翼穿層和順層構(gòu)造帶內(nèi),賦礦圍巖為下寒武統(tǒng)清虛洞組和上震旦統(tǒng)燈影組白云巖。無(wú)論是緩傾斜的似層狀礦體,還是陡傾斜的脈狀礦體,礦石中普遍發(fā)育角礫狀、脈狀、網(wǎng)脈狀和浸染狀構(gòu)造,金屬礦物主要為閃鋅礦,次為方鉛礦和黃鐵礦,脈石礦物以白云石、方解石為主,次為石英和重晶石。研究結(jié)果顯示,該礦床硫化物δ~(34)SV-CDT值變化范圍較寬,介于4.7‰~22.8‰之間,平均16.68‰,多數(shù)集中在18‰~22.5‰之間,遠(yuǎn)高于賦礦白云巖的δ~(34)S_(V-CDT)值(7.3‰)。硫化物總體呈現(xiàn)δ~(34)S_(閃鋅礦)δ~(34)S_(方鉛礦)δ~(34)S_(黃鐵礦),暗示S同位素分餾未達(dá)到平衡,成礦流體的δ~(34)S_(∑S)值應(yīng)高于硫化物的平均δ~(34)S值(16.68‰)。因此,成礦流體中的硫主要來(lái)源于賦礦海相碳酸鹽巖中的蒸發(fā)膏巖,是蒸發(fā)硫酸鹽礦物熱化學(xué)還原(TSR)作用的產(chǎn)物。硫化物具有正常Pb的組成特征,~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb及~(208)Pb/~(204)Pb變化范圍分別為17.8240~17.9701、15.6364~15.7651和37.8956~38.3230,與賦礦白云巖Pb同位素組成略有不同,但殼源特征明顯,很可能來(lái)源于區(qū)域基底巖石。綜上認(rèn)為,納雍枝鉛鋅礦床兼具層控和斷控成礦特征,成礦物質(zhì)主要由殼源巖石提供,硫化物沉淀受控于富金屬流體與富還原硫流體的混合作用,其形成是區(qū)域構(gòu)造與大規(guī)模成礦流體耦合作用的結(jié)果,屬于MVT礦床。
[Abstract]:Nayongzhi Pb-Zn deposit is located in the southwest margin of Yangzi block. It is a large Pb-Zn deposit in Wuzhishan anticline, northwest of Guizhou, which has made a breakthrough in recent years. It is also the largest Pb-Zn deposit found in Sichuan and Guizhou. The orebody is obviously controlled by strata and tectonics. It is stratiform, vein-like and lenticular, and occurs in the southeastern wing of Wuzhishan anticline and the bedding structural belt. The ore-bearing surrounding rock is dolomite of the lower Cambrian Qingxuidong formation and the Dengying formation of the Upper Sinian. Breccia, vein, net vein and disseminated structure are generally developed in ore, whether it is a gently inclined stratiform orebody or a steeply inclined vein orebody. The main metallic minerals are sphalerite, followed by galena and pyrite. The gangue minerals are dolomite, calcite, quartz and barite. The results show that there is a wide range of SV-CDT values of sulphides in the deposit, ranging from 4.7 鈥，

本文編號(hào)：1828149