甘肃早子沟金矿矿床成因——来自流体包裹体及H-O-S同位素的证据
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摘要
对早子沟金矿床进行了流体包裹体测温和H-O-S同位素分析.研究结果显示,包裹体的均一温度范围为120.8～257.5℃,主要集中于150～230℃(平均为178.0℃),冰点温度介于-3.6～-0.1℃(平均为-1.6℃).由此计算得到盐度介于0.18%～5.86%(平均2.61%),密度介于0.78～0.97 g/cm~3(平均0.91 g/cm~3).对6件石英样品的氢氧同位素测试结果显示,δ(D_(V-SMOW))介于-99.8～-91.40,δ(~(18)O_(H2O))介于-2.53～4.08,表明成矿流体可能由岩浆水或变质水与大气降水或地下水混合形成.黄铁矿样品的δ(~(34)S)均为负值,具有较窄的分布区间,介于-14.2～-7.6,说明成矿物质可能由区域内的岩浆岩或变质岩所提供.早子沟金矿可能形成于晚三叠世秦岭造山带后碰撞的伸展构造环境中,此时岩石圈拆沉导致软流圈上涌,引发下地壳大规模的岩浆作用,岩浆作用晚期热液携带成矿物质向上运移,经受了大气降水或地下水的混合作用,最终,含矿热液在构造破碎带中沉淀、富集成矿.
A fluid inclusion temperature testing and H-O-S isotopic analysis was performed of the Zaozigou gold deposit and the results showed that its homogenizing temperature ranged from 120.8 ℃ to257.5 ℃, mainly concentrating at 150-230 ℃(178.0 ℃ on average), and the freezing temperature rangedfrom-3.6 ℃ to-0.1 ℃(-1.6 ℃ on average). Accordingly, the salinity was calculated as from 0.18% to5.86%(2.61% on average) and bulk densities from 0.78 to 0.97 g/cm~3(0.91 g/cm~3 on average), respectively.The δ(DV-SMOW) and δ(~(18) O_(H_2O)) values of quartz from six samples ranged from-99.8 to-91.40 and from-2.53 to 4.08, respectively, indicating that the ore-forming fluid was probably magmatic or metamorphic in origin with contaminations of meteoric waters. The δ(~(34)S) values were all negative and ranged from-14.2 to-7.6 within a narrow distribution range, implying that the ore-forming materials were probably derived from magmatic or metamorphic rock. Together with previous studies, it was considered that the metallogenesis of the Zaozigou gold deposit was most likely associated with the post-collision extensional tectonic setting of the Qinling Orogen during the Late Triassic. The ore-forming processes can be summarized as the follow: the upwelling of asthenospheric mantle material caused by lithosphere delamination triggered a large-scale magmatism at the lower curst, and the late stage magmatic fluid carried ore-forming materials and moved upward. The ore-forming materials precipitated and settled in the fractures at the shallow crust.
A fluid inclusion temperature testing and H-O-S isotopic analysis was performed of the Zaozigou gold deposit and the results showed that its homogenizing temperature ranged from 120.8 ℃ to257.5 ℃, mainly concentrating at 150-230 ℃(178.0 ℃ on average), and the freezing temperature rangedfrom-3.6 ℃ to-0.1 ℃(-1.6 ℃ on average). Accordingly, the salinity was calculated as from 0.18% to5.86%(2.61% on average) and bulk densities from 0.78 to 0.97 g/cm~3(0.91 g/cm~3 on average), respectively.The δ(DV-SMOW) and δ(~(18) O_(H_2O)) values of quartz from six samples ranged from-99.8 to-91.40 and from-2.53 to 4.08, respectively, indicating that the ore-forming fluid was probably magmatic or metamorphic in origin with contaminations of meteoric waters. The δ(~(34)S) values were all negative and ranged from-14.2 to-7.6 within a narrow distribution range, implying that the ore-forming materials were probably derived from magmatic or metamorphic rock. Together with previous studies, it was considered that the metallogenesis of the Zaozigou gold deposit was most likely associated with the post-collision extensional tectonic setting of the Qinling Orogen during the Late Triassic. The ore-forming processes can be summarized as the follow: the upwelling of asthenospheric mantle material caused by lithosphere delamination triggered a large-scale magmatism at the lower curst, and the late stage magmatic fluid carried ore-forming materials and moved upward. The ore-forming materials precipitated and settled in the fractures at the shallow crust.
引文
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[21]刘斌.中高盐度NaCl-H2O包裹体的密度式和等容式及其应用[J].地质论评,2001,47(6):617-622.
[22]Clayton R N,O'Neil J R,Mayeda T K.Oxygen isotope exchange between quartz and water[J].Journal of Geophysical Research,1972,77(17):3057-3067.
[23]刘勇,刘云华,董福辰,等.甘肃枣子沟金矿床成矿时代精确测定及其地质意义[J].地球科学进展,2012,27(3):229-231.
[24]马倩.西秦岭阳山金矿带安坝金矿床流体包裹体特征及矿床成因[J].地质与勘探,2016,52(4):601-613.
[25]李康宁,金鼎国,蔡龙,等.早子沟金矿黄铁矿标型特征及其地质意义[J].甘肃地质,2014,23(2):33-40.
[26]韩吟文,马振东.地球化学[M].北京:地质出版社,2003.
[27]姚书振,周宗桂,吕新彪,等.秦岭成矿带成矿特征和找矿方向[J].西北地质,2006,39(2):156-178.
[28]毛景文.西秦岭地区造山型与卡林型金矿床[J].矿物岩石地球化学通报,2001,20(1):11-13.
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[30]王玉玺,第鹏飞,陈万峰,等.塔里木板块东南缘多坝沟金矿区花岗岩类年代学、地球化学特征及找矿意义[J].西北地质,2017,50(1):134-150.
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[32]莫江平,黄杰,杨明德,等.桂北构造蚀变岩型金矿的发现及成矿规律研究[J].矿产与地质,2007,21(3):237-239.
[33]邱正杰,范宏瑞,丛培章,等.造山型金矿床成矿过程研究进展[J].矿床地质,2015,34(1):21-38.
[34]隋吉祥,李建威.西秦岭夏河-合作地区枣子沟金矿床成矿时代与矿床成因[J].矿物学报,2013,52(增刊1):346-347.
[35]代文军,陈耀宇.甘肃枣子沟金矿区中性岩脉与成矿关系[J].黄金地质,2012,33(1):19-24.
[36]金维浚,张旗,何登发,等.西秦岭埃达克岩的SHRIMP定年及其构造意义[J].岩石学报,2005,21(3):959-966.
[37]徐学义,李婷,陈隽璐,等.西秦岭西段花岗岩浆作用与成矿[J].西北地质,2012,45(4):76-82.
[38]王文佳,何雨栗,杨国林,等.内蒙古大苏吉地区埃达克质花岗岩地球化学特征及其地质意义[J].兰州大学学报:自然科学版,2015,51(5):591-599.
[39]刘东晓,王玉玺,王金荣,等.塔里木板块东南缘早二叠世角闪石岩的发现及大地构造意义[J].兰州大学学报:自然科学版,2016,52(2):167-178.
[40]张国伟,董云鹏,赖绍聪,等.秦岭-大别造山带南缘勉略构造带与勉略缝合带[J].中国科学:D辑,2003,33(12):1121-1135.
[41]Li Lin,Meng Qing-ren,Pullen A,et al.Late permianearly middle Triassic back-arc basin development in West Qinling,China[J].Journal of Asian Earth Sciences,2014,87(5):116-129.
[42]Meng Dua-na,Niu Yao-ling,Kong Juan-juan,et al.Zircon U-Pb geochronology,Sr-Nd-Hf isotopic composition and geological significance of the Late Triassic Baijiazhuang and Lvjing granitic plutons in West Qinling Orogen[J].Lithos,2016,260(4):443-456.
[2]陈耀宇,代文军.枣子沟金矿地质特征及成矿模式探讨[J].新疆地质,2012,30(1):90-94.
[3]刘晓林.甘肃枣子沟金矿床地质特征及成因分析[J].甘肃地质,2011,20(1):52-56.
[4]吕新彪,曹晓峰,Sanogo M L S,等.枣子沟金矿地质特征、控矿构造及物质来源探讨[J].矿物学报,2009(增刊1):447-448.
[5]陈国忠,梁志录,王建龙,等.早子沟金矿岩石地球化学特征及其地质意义[J].甘肃地质,2012,21(4):23-31.
[6]梁志录,陈国忠,麻红顺,等.西秦岭早子沟金矿控矿断裂形成演化[J].大地构造与成矿学,2016,40(2):354-366.
[7]姜琪,王荣超.甘肃枣子沟金矿床形成环境及矿床成因[J].黄金科学技术,2010,18(4):37-40.
[8]刘春先,李亮,隋吉祥.甘肃枣子沟金矿的矿化特征及矿床成因[J].地质科技情报,2011,30(6):66-74.
[9]冯益民,曹宣择,张二朋,等.西秦岭造山带的演化、构造格局和性质[J].西北地质,2003,36(1):1-10.
[10]姜春发,王宗起,李锦铁.中央造山带开合构造[M].北京:地质出版社,2000.
[11]李春昱.中国板块构造的轮廊[J].中国地质科学院院报,1980,2(1):11-22.
[12]张国伟,孟庆任,于在平,等.秦岭造山带的造山过程及其动力学特征[J].中国科学:D辑,1996,26(3):193-200.
[13]Annels A E,Roberts D E.Turbidite-hosted gold mineralization at the Dolaucothi gold mines,Dyfed,Wales,United Kingdom[J].Economic Geology,1989,84(5):1293-1314.
[14]潘桂棠,肖庆辉,陆松年,等.中国大地构造单元划分[J].中国地质,2009,26(1):1-4.
[15]王宗起,闫全人,闫臻,等.秦岭造山带主要大地构造单元的新划分[J].地质学报,2009,83(11):1527-1546.
[16]卢焕章,范宏瑞,倪培.流体包裹体[M].北京:科学出版社,2004:406-419.
[17]Roedder E.Fluid inclusions:mineralogical society of America[J].Reviews in Mineralogy,1984,12:644-652.
[18]Hall D L,Sterner S M,Bodnar R J.Freeing point depression of Na-Cl-KCl-H2O solutions[J].Econmic Geology,1988,83:197-202.
[19]Potter R WⅡ,Clynne M A,Brown D L.Freezing pointdepres-sion of aqueous sodium chloride solutions[J].Econmic Geology,1978,73:284-285.
[20]刘斌,段光贤.NaCl-H2O溶液包裹体的密度式和等容式及其应用[J].矿物学报,1987,7(4):345-353.
[21]刘斌.中高盐度NaCl-H2O包裹体的密度式和等容式及其应用[J].地质论评,2001,47(6):617-622.
[22]Clayton R N,O'Neil J R,Mayeda T K.Oxygen isotope exchange between quartz and water[J].Journal of Geophysical Research,1972,77(17):3057-3067.
[23]刘勇,刘云华,董福辰,等.甘肃枣子沟金矿床成矿时代精确测定及其地质意义[J].地球科学进展,2012,27(3):229-231.
[24]马倩.西秦岭阳山金矿带安坝金矿床流体包裹体特征及矿床成因[J].地质与勘探,2016,52(4):601-613.
[25]李康宁,金鼎国,蔡龙,等.早子沟金矿黄铁矿标型特征及其地质意义[J].甘肃地质,2014,23(2):33-40.
[26]韩吟文,马振东.地球化学[M].北京:地质出版社,2003.
[27]姚书振,周宗桂,吕新彪,等.秦岭成矿带成矿特征和找矿方向[J].西北地质,2006,39(2):156-178.
[28]毛景文.西秦岭地区造山型与卡林型金矿床[J].矿物岩石地球化学通报,2001,20(1):11-13.
[29]Kerrich R,Goldfarb R,Groves D,et al.超大型金成矿省的地球动力学背景(摘要)[J].中国科学:D辑,2000,30(增刊1):14-15.
[30]王玉玺,第鹏飞,陈万峰,等.塔里木板块东南缘多坝沟金矿区花岗岩类年代学、地球化学特征及找矿意义[J].西北地质,2017,50(1):134-150.
[31]王京彬,王军升,李博泉.新疆准噶尔地区与火山-浅成岩有关的金矿成矿系列[J].有色金属矿产与勘查,1997,6(增刊1):25-37.
[32]莫江平,黄杰,杨明德,等.桂北构造蚀变岩型金矿的发现及成矿规律研究[J].矿产与地质,2007,21(3):237-239.
[33]邱正杰,范宏瑞,丛培章,等.造山型金矿床成矿过程研究进展[J].矿床地质,2015,34(1):21-38.
[34]隋吉祥,李建威.西秦岭夏河-合作地区枣子沟金矿床成矿时代与矿床成因[J].矿物学报,2013,52(增刊1):346-347.
[35]代文军,陈耀宇.甘肃枣子沟金矿区中性岩脉与成矿关系[J].黄金地质,2012,33(1):19-24.
[36]金维浚,张旗,何登发,等.西秦岭埃达克岩的SHRIMP定年及其构造意义[J].岩石学报,2005,21(3):959-966.
[37]徐学义,李婷,陈隽璐,等.西秦岭西段花岗岩浆作用与成矿[J].西北地质,2012,45(4):76-82.
[38]王文佳,何雨栗,杨国林,等.内蒙古大苏吉地区埃达克质花岗岩地球化学特征及其地质意义[J].兰州大学学报:自然科学版,2015,51(5):591-599.
[39]刘东晓,王玉玺,王金荣,等.塔里木板块东南缘早二叠世角闪石岩的发现及大地构造意义[J].兰州大学学报:自然科学版,2016,52(2):167-178.
[40]张国伟,董云鹏,赖绍聪,等.秦岭-大别造山带南缘勉略构造带与勉略缝合带[J].中国科学:D辑,2003,33(12):1121-1135.
[41]Li Lin,Meng Qing-ren,Pullen A,et al.Late permianearly middle Triassic back-arc basin development in West Qinling,China[J].Journal of Asian Earth Sciences,2014,87(5):116-129.
[42]Meng Dua-na,Niu Yao-ling,Kong Juan-juan,et al.Zircon U-Pb geochronology,Sr-Nd-Hf isotopic composition and geological significance of the Late Triassic Baijiazhuang and Lvjing granitic plutons in West Qinling Orogen[J].Lithos,2016,260(4):443-456.
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