贵州纳雍枝铅锌矿床还原S的形成机制:NanoSIMS原位S同位素约束
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摘要
位于黔西北地区的纳雍枝铅锌矿床,是目前报道的贵州省境内规模最大的铅锌矿床,已探明铅锌储量超过130万吨。纳雍枝铅锌矿床赋存于下寒武统清虚洞组和上震旦统灯影组碳酸盐岩中,受岩性和构造的双重控制,断层和背斜是主要控矿构造,铅锌成矿地质特征与MVT铅锌矿床较为相似。纳米离子探针(NanoSIMS)获得的纳雍枝铅锌矿床中黄铁矿和闪锌矿原位δ~(34)S分析数据表明,黄铁矿的δ~(34)S值变化范围在-16.6‰～+27.0‰之间,闪锌矿的δ~(34)S值范围为+11.8‰～+33.0‰,这与传统全矿物法获得的黄铁矿(δ~(34)S=+4.7‰～+18.1‰)和闪锌矿(δ~(34)S=+11.3‰～+25.22‰)的S同位素组成明显差异。根据矿物组合和晶体形态特征等,本文认为早期胶状、集合体状或交代残余黄铁矿(δ~(34)S=-16.6‰～-14.9‰)的还原S是由细菌引起的海相硫酸盐还原(BSR)产物,而晚期它形粒状黄铁矿和闪锌矿(δ~(34)S=+11.8‰～+33.0‰)的还原S是海相硫酸盐热化学还原作用(TSR)的产物。因此,纳雍枝铅锌矿床还原S的形成经历了BSR和TSR过程。综合以往地质地球化学研究资料,本文认为五指山地区铅锌矿床的空间分布受原地蒸发膏岩层的控制,BSR发生在成矿前,而TSR则是热流体加入后诱发的,矿床形成是构造-岩性-流体耦合作用的结果。
Located in the northwestern part of Guizhou Province, the Nayongzhi Pb-Zn deposit is the largest Pb-Zn deposit reported in Guizhou Province, with over 1.3 Mt of proved Pb + Zn metal reserves. It occurs in carbonate rocks of Lower Cambrian Qingxudong Formation and Upper Sinian Dengying Formation, and within ore-controlling structures of reverse fault and anticline. It is controlled by both lithology and structure. Its metallogenic characteristics are relatively similar to those of the typical MVT Pb-Zn deposit. The NanoSIMS in situ analytical results of δ~(34)S values of pyrite and sphalerite grains in the Nayongzhi Pb-Zn deposit show that the δ~(34)S values of pyrite and sphalerite grains range from-16.6‰ to +27.0‰, and from +11.8‰ to +33.0‰, respectively, which are significantly different from the ranges of δ~(34)S values of pyrite separates(δ~(34)S = +4.7‰ to +18.1‰) and sphalerite separates(δ~(34)S = +11.3‰ to +25.22‰) obtained by the conventional bulk-mineral method. Based on mineral assemblage and crystal morphology characteristics of ores, this paper has considered that the reduced S of early colloidal, aggregate-like or replacement remnant pyrites(δ~(34)S =-16.6‰ to-14.9‰) could be formed by bacterial sulfate reduction(BSR), whereas the reduced S of late xenomorphic granular pyrite and sphalerite(δ~(34)S = +11.8‰ to +33.0‰) could be the product of thermochemical reduction(TSR) of marine sulfate. Combined with previous geological and geochemical data, this paper has proposed that the spatial distribution of Pb-Zn deposits in the Wuzhishan area is controlled by local gypsum-bearing evaporated sulfate layers, the BSR occurred before Pb-Zn mineralization and the TSR could be trigged by the input of hydrothermal fluids, and the formation of Pb-Zn deposits could be resulted from the structure-lithology-fluid coupling.
Located in the northwestern part of Guizhou Province, the Nayongzhi Pb-Zn deposit is the largest Pb-Zn deposit reported in Guizhou Province, with over 1.3 Mt of proved Pb + Zn metal reserves. It occurs in carbonate rocks of Lower Cambrian Qingxudong Formation and Upper Sinian Dengying Formation, and within ore-controlling structures of reverse fault and anticline. It is controlled by both lithology and structure. Its metallogenic characteristics are relatively similar to those of the typical MVT Pb-Zn deposit. The NanoSIMS in situ analytical results of δ~(34)S values of pyrite and sphalerite grains in the Nayongzhi Pb-Zn deposit show that the δ~(34)S values of pyrite and sphalerite grains range from-16.6‰ to +27.0‰, and from +11.8‰ to +33.0‰, respectively, which are significantly different from the ranges of δ~(34)S values of pyrite separates(δ~(34)S = +4.7‰ to +18.1‰) and sphalerite separates(δ~(34)S = +11.3‰ to +25.22‰) obtained by the conventional bulk-mineral method. Based on mineral assemblage and crystal morphology characteristics of ores, this paper has considered that the reduced S of early colloidal, aggregate-like or replacement remnant pyrites(δ~(34)S =-16.6‰ to-14.9‰) could be formed by bacterial sulfate reduction(BSR), whereas the reduced S of late xenomorphic granular pyrite and sphalerite(δ~(34)S = +11.8‰ to +33.0‰) could be the product of thermochemical reduction(TSR) of marine sulfate. Combined with previous geological and geochemical data, this paper has proposed that the spatial distribution of Pb-Zn deposits in the Wuzhishan area is controlled by local gypsum-bearing evaporated sulfate layers, the BSR occurred before Pb-Zn mineralization and the TSR could be trigged by the input of hydrothermal fluids, and the formation of Pb-Zn deposits could be resulted from the structure-lithology-fluid coupling.
引文
[1]周家喜,黄智龙,周国富,等.黔西北赫章天桥铅锌矿床成矿物质来源:S、Pb同位素和REE制约[J].地质论评,2010,56(4):513-524.
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[7]彭松,金中国,林贵生,等.贵州五指山铅锌矿区控矿因素及成矿模式研究--以纳雍枝矿床为例[J].矿产勘查,2016,7(3):463-470.
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[10]Zhou JX,Wang XC,Wilde SA,et al.New insights into the metallogeny of MVT Zn-Pb deposits:A case study from the Nayongzhi in South China,using field data,fluid compositions,and in situ S-Pb isotopes[J].American Mineralogist,2018,103(1):91-108.
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[13]朱路艳,苏文超,沈能平,等.黔西北地区铅锌矿床流体包裹体与硫同位素地球化学研究[J].岩石学报,2016,32(11):3431-3440.
[14]周家喜,黄智龙,周国富,等.贵州天桥铅锌矿床分散元素赋存状态及规律[J].矿物学报,2009(4):471-480.
[15]金中国,周家喜,郑明泓,等.贵州普定五指山地区铅锌矿床成矿模式[J].矿床地质,2017,36(5):1169-1184.
[16]陈伟,孔志岗,刘凤祥,等.贵州纳雍枝铅锌矿床地质、地球化学及矿床成因[J].地质学报,2017,91(6):1269-1284.
[17]金灿海,李坤,黄林,等.黔西北纳雍枝铅锌矿硫铅同位素组成特征及成矿物质来源[J].矿物岩石,2015,35(3):81-88.
[18]Claypool GE,Holser WT,Kaplan IR,et al.The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation[J].Chemical Geology,1980,28:199-260.
[19]Seal I R.Sulfur isotope geochemistry of sulfide minerals[J].Reviews in Mineralogy and Geochemistry,2006,61(1):633-677.
[20]Ohmoto H.Systematics of sulfur and carbon isotopes in hydrothermal ore deposits[J].Economic Geology,1972,67:1541-1544.
[21]J?rgenson BB,Isaksen MF,Jannasch HW.Bacterial sulfate reduction above 100°C in deep sea hydrothermal vent sediments[J].Science,1992,258:1756-1757.
[22]Basuki NI,Taylor BE,Spooner ETC.Sulfur isotope evidence for thermo-chemical reduction of dissolved sulfate in Mississippi valley type zinc-lead mineralization,Bongara area,northern Peru[J].Economic Geology,2008,103:183-799.
[23]Leach DL,Sangster D,Kelley KD,et al.Sediment-hosted lead-zinc deposits:A global perspective[J].Economic Geology,2005,100th Ann 561-607.
[24]崔银亮,周家喜,黄智龙,等.云南富乐铅锌矿床地质、地球化学及成因[J].岩石学报,2018,34(1):194-206.
[25]周家喜,黄智龙,高建国,等.滇东北茂租大型铅锌矿床成矿物质来源及成矿机制[J].矿物岩石,2012,32(3):62-69.
[27]熊伟,程鹏林,周高,等.黔西北铅锌成矿区成矿金属来源的铅同位素示踪[J].矿物学报,2015,35(4):425-429.
[2]黄智龙,胡瑞忠,苏文超,等.西南大面积低温成矿域:研究意义、历史及新进展[J].矿物学报,2011,31(3):309-314.
[3]胡瑞忠,付山岭,肖加飞.华南大规模低温成矿的主要科学问题[J].岩石学报,2016,32(11):3239-3251.
[4]Zhou JX,Xiang ZZ,Zhou MF,et al.The giant Upper Yangtze Pb-Zn province in SW China:Reviews,new advances and a new genetic model[J].Journal of Asian Earth Sciences,2018,154:280-315.
[5]陈国勇,王亮,范玉梅,等.贵州五指山铅锌矿田深部找矿远景分析[J].地质与勘探,2015,51(5):859-869.
[6]金中国,周家喜,黄智龙,等.贵州普定纳雍枝铅锌矿矿床成因:S和原位Pb同位素证据[J].岩石学报,2016,32(11):3441-3455.
[7]彭松,金中国,林贵生,等.贵州五指山铅锌矿区控矿因素及成矿模式研究--以纳雍枝矿床为例[J].矿产勘查,2016,7(3):463-470.
[8]Zhang J,Lin Y,Yang W,et al.Improved precision and spatial resolution of sulfur isotope analysis using NanoSIMS[J].Journal of Analytical Atomic Spectrometry,2014,29:1934-1943.
[9]Zhou JX,Luo K,Wang XC,et al.Ore genesis of the Fule Pb-Zn deposit and its relationship with the Emeishan Large Igneous Province:Evidence from mineralogy,bulk C-O-S and in situ S-Pb isotopes[J].Gondwana Research,2018,54:161-179.
[10]Zhou JX,Wang XC,Wilde SA,et al.New insights into the metallogeny of MVT Zn-Pb deposits:A case study from the Nayongzhi in South China,using field data,fluid compositions,and in situ S-Pb isotopes[J].American Mineralogist,2018,103(1):91-108.
[11]金中国.黔西北地区铅锌矿控矿因素、成矿规律与找矿预测[M].北京:冶金工业出版社,2008,1-105.
[12]周家喜,黄智龙,周国富,等.黔西北天桥铅锌矿床热液方解石C、O同位素和REE地球化学[J].大地构造与成矿学,2012,36(1):93-101.
[13]朱路艳,苏文超,沈能平,等.黔西北地区铅锌矿床流体包裹体与硫同位素地球化学研究[J].岩石学报,2016,32(11):3431-3440.
[14]周家喜,黄智龙,周国富,等.贵州天桥铅锌矿床分散元素赋存状态及规律[J].矿物学报,2009(4):471-480.
[15]金中国,周家喜,郑明泓,等.贵州普定五指山地区铅锌矿床成矿模式[J].矿床地质,2017,36(5):1169-1184.
[16]陈伟,孔志岗,刘凤祥,等.贵州纳雍枝铅锌矿床地质、地球化学及矿床成因[J].地质学报,2017,91(6):1269-1284.
[17]金灿海,李坤,黄林,等.黔西北纳雍枝铅锌矿硫铅同位素组成特征及成矿物质来源[J].矿物岩石,2015,35(3):81-88.
[18]Claypool GE,Holser WT,Kaplan IR,et al.The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation[J].Chemical Geology,1980,28:199-260.
[19]Seal I R.Sulfur isotope geochemistry of sulfide minerals[J].Reviews in Mineralogy and Geochemistry,2006,61(1):633-677.
[20]Ohmoto H.Systematics of sulfur and carbon isotopes in hydrothermal ore deposits[J].Economic Geology,1972,67:1541-1544.
[21]J?rgenson BB,Isaksen MF,Jannasch HW.Bacterial sulfate reduction above 100°C in deep sea hydrothermal vent sediments[J].Science,1992,258:1756-1757.
[22]Basuki NI,Taylor BE,Spooner ETC.Sulfur isotope evidence for thermo-chemical reduction of dissolved sulfate in Mississippi valley type zinc-lead mineralization,Bongara area,northern Peru[J].Economic Geology,2008,103:183-799.
[23]Leach DL,Sangster D,Kelley KD,et al.Sediment-hosted lead-zinc deposits:A global perspective[J].Economic Geology,2005,100th Ann 561-607.
[24]崔银亮,周家喜,黄智龙,等.云南富乐铅锌矿床地质、地球化学及成因[J].岩石学报,2018,34(1):194-206.
[25]周家喜,黄智龙,高建国,等.滇东北茂租大型铅锌矿床成矿物质来源及成矿机制[J].矿物岩石,2012,32(3):62-69.
[27]熊伟,程鹏林,周高,等.黔西北铅锌成矿区成矿金属来源的铅同位素示踪[J].矿物学报,2015,35(4):425-429.