贵州泥堡金矿床构造蚀变体岩相学及地球化学特征
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摘要
贵州泥堡金矿构造蚀变体(SBT)为产出于茅口组(P_2m)和龙潭组(P_3l)或峨眉山玄武岩(P_3β)之间沉积间断面-不整合界面附近的一套硅质蚀变岩石组合。采用光学显微镜及ICP-MS研究SBT样品岩相学及元素地球化学特征,结果显示,SBT矿石样品中主要矿物有石英、黄铁矿、褐铁矿、萤石、白云石和辉锑矿等,蚀变类型主要为黄铁矿化、白云石化和硅化,微观结构主要为砂状、岩屑-凝灰碎屑结构、交代结构等,构造主要有浸染状、块状、角砾状、条带状和脉状构造。SBT微量元素标准化曲线以Au、As、Sb、Hg、Te的强烈富集,Li、Sc、Cr的亏损和Cd、Ta的富集为特征。稀土元素CI球粒陨石标准化配分模式图表现为轻稀土富集的右倾型,LREE/HREE为6. 98～19. 91,"四分组"效应明显,重稀土分馏不明显,解释为受热液作用强烈; SBT微量元素标准化图及稀土元素配分曲线均表现出与围岩相似,表明继承了原岩的元素组成;δEu为0. 80～1. 84,显示Eu从明显负异常到明显的正异常;δCe为0. 72～1. 25,显示Ce从明显负异常到弱正异常,认为流体来源于深部或至少经历过对富含斜长石源区的水-岩反应,而不是含矿地层的改造热液。
SBT of Nibao gold deposit is a set of siliceous altered rock assemblages that occur near the inter-sedimentary section-unconformity interface between P_2 m and P_3 l or P_3β. The petrographic and elemental geochemistry characteristics of SBT samples are studied with optical microscope and ICP-MS. The result shows that the main minerals in SBT samples are quartz,pyrite,limonite,fluorite,dolomite and stibnite; the alteration types are mainly pyrite mineralization,dolomitization and silicidation; the microstructure is mainly sandlike,lithic-tuff clastic structure,metasomatic structure and so on; the structure is mainly disseminated,massive,brecciaous,stripped and vein-like. The microelement standardized curve of SBT is featured with strong enrichment of Au,As,Sb,Hg and Te,the depletion of Li,Sc and Cr and the enrichment of Cd and Ta. The chondrite-normalized distribution pattern of CI shows that LREE/HREE is 6. 98-19. 91,with enrichment of light rare earth elements. The tetrad effect is obvious,but the distribution of heavy rare earth element is not obvious,which is explained by the strong effect of hydrothermal solution. SBT trace element standardized diagram and rare earth element distribution curve show similarity with surrounding rock,indicating that element composition of original rock is inherited. The δEu is 0. 80-1. 84,indicating a change of obvious negative anomaly to obvious positive anomaly of Eu. δCe is0. 72-1. 25,which indicates that a change of obvious negative anomaly to weak positive anomaly of Ce. It is believed that the fluid originated from deep areas or at least experienced water-rock reaction to plagioclase source area,rather than from hydrothermal solution of ore-bearing strata.
SBT of Nibao gold deposit is a set of siliceous altered rock assemblages that occur near the inter-sedimentary section-unconformity interface between P_2 m and P_3 l or P_3β. The petrographic and elemental geochemistry characteristics of SBT samples are studied with optical microscope and ICP-MS. The result shows that the main minerals in SBT samples are quartz,pyrite,limonite,fluorite,dolomite and stibnite; the alteration types are mainly pyrite mineralization,dolomitization and silicidation; the microstructure is mainly sandlike,lithic-tuff clastic structure,metasomatic structure and so on; the structure is mainly disseminated,massive,brecciaous,stripped and vein-like. The microelement standardized curve of SBT is featured with strong enrichment of Au,As,Sb,Hg and Te,the depletion of Li,Sc and Cr and the enrichment of Cd and Ta. The chondrite-normalized distribution pattern of CI shows that LREE/HREE is 6. 98-19. 91,with enrichment of light rare earth elements. The tetrad effect is obvious,but the distribution of heavy rare earth element is not obvious,which is explained by the strong effect of hydrothermal solution. SBT trace element standardized diagram and rare earth element distribution curve show similarity with surrounding rock,indicating that element composition of original rock is inherited. The δEu is 0. 80-1. 84,indicating a change of obvious negative anomaly to obvious positive anomaly of Eu. δCe is0. 72-1. 25,which indicates that a change of obvious negative anomaly to weak positive anomaly of Ce. It is believed that the fluid originated from deep areas or at least experienced water-rock reaction to plagioclase source area,rather than from hydrothermal solution of ore-bearing strata.
引文
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刘建中,王泽鹏,杨成富,等,2017.南盘江-右江成矿区金矿成矿模式构想[J].矿物学报,37(增刊):139-140.
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王秀璋,程景平,张宝贵,等,1992.中国改造型金矿床地球化学[M].北京:科学出版社.
王小春,1998.论中国微细浸染型金矿的成矿机理[J].冶金地质动态(10):7-9.
夏勇,2005.贵州贞丰县水银洞金矿床成矿特征和金的超常富集机制研究[D].贵州:中国科学院地球化学研究所.
夏勇,张瑜,苏文超,等,2009.黔西南水银洞层控超大型卡林型金矿床成矿模式及成矿预测研究[J].地质学报,83(10):1473-1482.
杨科伍,1992.戈塘式金矿床之成因及找矿远景初探:兼论紫木凼式金矿[J].贵州地质,9(4):299-306.
杨科佑,陈丰,苏文超,等,1994.滇黔桂地区卡林型金矿的地质地球化学特征及找矿前景[C]//中加金矿床对比研究:CIDA项目Ⅱ-17文集.北京:地震出版社:17-30.
朱赖民,金景福,何明友,等,1997.初论黔西南微细浸染型金矿床深源流体成矿[J].矿物岩石地球化学通报,16(3):173-177.
朱赖民,金景福,何明友,等,1998.黔西南微细浸染型金矿床深部物质来源的同位素地球化学研究[J].吉林大学学报(地球科学版),28(1):37-42.
庄汉平,卢家烂,傅家谟,等,1998.黔西南两种成因类型的卡林型金矿床[J].科学通报,43(9):977-982.
张瑜,夏勇,王泽鹏,等,2010.贵州簸箕田金矿单矿物稀土元素和同位素地球化学特征[J].地学前缘,17(2):385-395.
Boynton W V,1984.Cosmochemistry of the rare earth elements:meteorite studies[J].Developments in Geochemistry,2(2):63-114.
迟清华,鄢明才,2007.应用地球化学元素丰度数据手册[M].北京:地质出版社.
陈文斌,韦标根,杨天才,等,2009.贵州普安县泥堡金矿床地质特征与找矿潜力[J].贵州地质,26(3):170-176.
范军,肖荣阁,1997.矿床及其组合是地壳演化的标志物:右江幔隆的发生、发展与滇黔桂卡林型金矿关系探讨[J].矿物学报,17(4):457-462.
国家辉,黄德保,1992.桂西北超微粒型金矿及其成矿和找矿模式[M].北京:地震出版社.
刘显凡,倪师军,苏文超,1996.滇黔桂微细浸染型金矿同位素地球化学特征与深源流体成矿[J].矿物岩石,16(4):106-111.
李红阳,侯增谦,1998.初论幔柱构造成矿体系[J].矿床地质,17(3):247-255.
刘显凡,苏文超,朱赖民,1999.滇黔桂微细浸染型金矿深源流体成矿机理探讨[J].地质与勘探,35(1):14-19.
李红阳,高振敏,杨竹森,等,2000.我国西南地区卡林型金矿成矿模式讨论[J].矿物岩石地球化学通报,19(4):360-361.
刘建中,刘川勒,2005.贵州水银洞金矿床成因探讨及成矿模式[J].贵州地质,22(1):9-13.
刘建中,邓一明,邱林,等,2006.中国第一个Ⅰ类型金矿床:水银洞金矿地质[J].矿床地质,25(增刊):175-178.
刘建中,夏勇,张兴春,等,2008.层控卡林型金矿床矿床模型:贵州水银洞超大型金矿[J].黄金科学技术,16(3):1-5.
刘建中,夏勇,陶琰,等,2014.贵州西南部SBT与金锑矿成矿找矿[J].贵州地质,31(4):267-272.
刘建中,王泽鹏,杨成富,等,2015.贵州西南部SBT分布区金锑矿成矿机制与成矿模式[J].矿物学报,35(增刊):895-896.
刘建中,王泽鹏,杨成富,等,2017.南盘江-右江成矿区金矿成矿模式构想[J].矿物学报,37(增刊):139-140.
刘建中,夏勇,陶琰,等,2018.贵州西南部SBT研究[M].武汉:中国地质大学(武汉).
聂爱国,2009.峨眉地幔热柱活动形成黔西南卡林型金矿成因机制[M].贵阳:贵州科技出版社.
庞保成,林畅松,2001.右江盆地微细浸染型金矿的成因探讨[J].地质与勘探,37(4):9-13.
王秀璋,程景平,张宝贵,等,1992.中国改造型金矿床地球化学[M].北京:科学出版社.
王小春,1998.论中国微细浸染型金矿的成矿机理[J].冶金地质动态(10):7-9.
夏勇,2005.贵州贞丰县水银洞金矿床成矿特征和金的超常富集机制研究[D].贵州:中国科学院地球化学研究所.
夏勇,张瑜,苏文超,等,2009.黔西南水银洞层控超大型卡林型金矿床成矿模式及成矿预测研究[J].地质学报,83(10):1473-1482.
杨科伍,1992.戈塘式金矿床之成因及找矿远景初探:兼论紫木凼式金矿[J].贵州地质,9(4):299-306.
杨科佑,陈丰,苏文超,等,1994.滇黔桂地区卡林型金矿的地质地球化学特征及找矿前景[C]//中加金矿床对比研究:CIDA项目Ⅱ-17文集.北京:地震出版社:17-30.
朱赖民,金景福,何明友,等,1997.初论黔西南微细浸染型金矿床深源流体成矿[J].矿物岩石地球化学通报,16(3):173-177.
朱赖民,金景福,何明友,等,1998.黔西南微细浸染型金矿床深部物质来源的同位素地球化学研究[J].吉林大学学报(地球科学版),28(1):37-42.
庄汉平,卢家烂,傅家谟,等,1998.黔西南两种成因类型的卡林型金矿床[J].科学通报,43(9):977-982.
张瑜,夏勇,王泽鹏,等,2010.贵州簸箕田金矿单矿物稀土元素和同位素地球化学特征[J].地学前缘,17(2):385-395.
Boynton W V,1984.Cosmochemistry of the rare earth elements:meteorite studies[J].Developments in Geochemistry,2(2):63-114.