内蒙古敖汉旗金路金矿床地质特征及成矿流体研究
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摘要
金路金矿床位于华北克拉通和中亚造山带的结合部位,矿体受北东向韧-脆性断裂控制,赋矿围岩为太古宇小塔子沟组变质岩和三叠纪片麻状二长花岗岩。以流体包裹体和电子探针分析为研究手段,讨论了成矿流体的特征、演化及其与金矿化的关系。其热液成矿过程可划分为乳白色石英阶段(Ⅰ阶段)、石英-黄铁矿阶段(Ⅱ阶段)、石英-多金属硫化物阶段(Ⅲ阶段)和碳酸盐阶段(Ⅳ阶段) 4个阶段,自然金主要产于Ⅲ阶段的石英和黄铁矿中,以粒间金、裂隙金和包体金的形式产出,成色较高。石英中原生包裹体主要有水溶液包裹体、含微量CO2水包裹体、含子矿物多相包裹体3种类型。Ⅰ阶段石英中以水溶液包裹体和含微量CO2水包裹体为主,均一温度较高,为365～405℃,盐度为7. 9%～11. 7%,密度为0. 61～0. 70 g/cm3;Ⅱ阶段石英中3种类型包裹体均发育,均一温度为335～390℃,盐度为4. 3%～36. 1%,密度为0. 62～0. 79 g/cm3;Ⅲ阶段(主阶段)石英中发育3种类型包裹体,均一温度为270～367℃,盐度为1. 7%～37. 8%,密度为0. 64～1. 1 g/cm3。成矿流体属H2O-Na Cl-CO2体系,成矿温度和流体盐度呈逐渐降低趋势,密度则呈现逐渐增大趋势。根据流体包裹体岩相学特征和矿床地质特征,认为流体沸腾作用和硫化作用是本矿区金沉淀成矿的主要机制。综合分析认为矿床成因类型为岩浆热液矿床。
The Jinlu gold deposit is located in the convergence of North China Craton and central Asian orogenic belt. Its ore-bodies controlled by the NE trending ductile-brittle faults,are hosted in metamorphic rocks of the Archean Xiaotazigou Formation and Triassic gneissic monzonitic granite. Based on the studies of fluid inclusions and electron probe,the aim of this paper is to discuss the characteristics and evolution of ore-forming fluids and to provide an insight into the ore genesis. The ore-forming process can be divided into four metallogenic stages,respectively named the white quartz stage( Ⅰ),the quartz-pyrite stage( Ⅱ),the quartz-polymetallic sulfidestage( Ⅲ) and carbonate stage( Ⅳ). Native gold with very high fineness are mainly produced in the Ⅲ-stage quartz and pyrite in the form of intergranular gold,fissured gold and inclusion gold. Petrographic observation indicates that fluid inclusions of the deposit can be divided into three types,i. e.,aqueous inclusions,CO2-bearing aqueous inclusions and daughter mineral-bearing multiphase inclusions. The Ⅰ-stage quartz mainly contains aqueous inclusions and CO2-bearing aqueous inclusions. The homogenization temperatures,salinities and densities are in the ranges of 365 ℃ to 405 ℃,7. 9% to 11. 7% and 0. 61 g/cm3 to 0. 70 g/cm3. All three types of inclusions are trapped in the Ⅱ-stage quartz. The homogenization temperatures,salinities and densities vary from 335 ℃ to 390 ℃,4. 3% to 35. 5% and 0. 62 g/cm3 to 0. 79 g/cm3. All three types of inclusions are found in the Ⅲ-stage quartz. The homogenization temperatures,salinities and densities have a range of 270 ℃to 367 ℃,1. 7% to 37. 8% and 0. 64 g/cm3 to 1. 1 g/cm3. The studies of fluid inclusions in three metallogenic stages indicate that the ore-forming fluids belong to H2 O-NaCl-CO2 system. The metallogenetic temperatures and fluid salinities gradually decreased and the densities showed a slightly increasing trend. Based on fluid inclusions and geologic characteristics,it is suggested that fluid boiling and sulfofication may be the main mechanism for the gold precipitation and enrichment in this deposit. The genesis of the Jinlu gold deposit is a magmatic hydrothermal gold deposit.
The Jinlu gold deposit is located in the convergence of North China Craton and central Asian orogenic belt. Its ore-bodies controlled by the NE trending ductile-brittle faults,are hosted in metamorphic rocks of the Archean Xiaotazigou Formation and Triassic gneissic monzonitic granite. Based on the studies of fluid inclusions and electron probe,the aim of this paper is to discuss the characteristics and evolution of ore-forming fluids and to provide an insight into the ore genesis. The ore-forming process can be divided into four metallogenic stages,respectively named the white quartz stage( Ⅰ),the quartz-pyrite stage( Ⅱ),the quartz-polymetallic sulfidestage( Ⅲ) and carbonate stage( Ⅳ). Native gold with very high fineness are mainly produced in the Ⅲ-stage quartz and pyrite in the form of intergranular gold,fissured gold and inclusion gold. Petrographic observation indicates that fluid inclusions of the deposit can be divided into three types,i. e.,aqueous inclusions,CO2-bearing aqueous inclusions and daughter mineral-bearing multiphase inclusions. The Ⅰ-stage quartz mainly contains aqueous inclusions and CO2-bearing aqueous inclusions. The homogenization temperatures,salinities and densities are in the ranges of 365 ℃ to 405 ℃,7. 9% to 11. 7% and 0. 61 g/cm3 to 0. 70 g/cm3. All three types of inclusions are trapped in the Ⅱ-stage quartz. The homogenization temperatures,salinities and densities vary from 335 ℃ to 390 ℃,4. 3% to 35. 5% and 0. 62 g/cm3 to 0. 79 g/cm3. All three types of inclusions are found in the Ⅲ-stage quartz. The homogenization temperatures,salinities and densities have a range of 270 ℃to 367 ℃,1. 7% to 37. 8% and 0. 64 g/cm3 to 1. 1 g/cm3. The studies of fluid inclusions in three metallogenic stages indicate that the ore-forming fluids belong to H2 O-NaCl-CO2 system. The metallogenetic temperatures and fluid salinities gradually decreased and the densities showed a slightly increasing trend. Based on fluid inclusions and geologic characteristics,it is suggested that fluid boiling and sulfofication may be the main mechanism for the gold precipitation and enrichment in this deposit. The genesis of the Jinlu gold deposit is a magmatic hydrothermal gold deposit.
引文
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[12]苗来成,范蔚茗,翟明国,等.金厂沟梁—二道沟金矿田内花岗岩类侵入体锆石的离子探针U-Pb年代学及意义[J].岩石学报,2003,19(1):71-80.
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[14]牛树银,王宝德,张建珍,等.内蒙古金厂沟梁金矿的构造特征及深部找矿预测[J].大地构造与成矿学,2011,35(3):348-354.
[15]段培新,李长民,刘翠,等.内蒙古赤峰金厂沟梁金矿区花岗岩类年代学、地球化学特征及其地质意义[J].岩石学报,2014,30(11):3189-3202.
[16] POTTER R W,CLYNNE M A,BROWN D L. Freezing point depression of aqueous sodium chloride solutions[J]. Economic Geology,1978,73(2):284-285.
[17]刘斌,段光贤. Na Cl-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):345-352.
[18] COLLINS P L F. Gas hydrates in CO2-bearing fluid inclusion and the use of freezing data for estimation of salinity[J]. Economic Geology,1979,74(6):1435-1444.
[19] HALL D L,STERNER S M,BODNAR R J. Freezing point depression of Na Cl-KCl-H2O solutions[J]. Economic Geology,1988,83(1):197-202.
[20] BODNAR R J. A method of calculating fluid inclusion volumes based on vapor bubble diameters and P-V-T-X properties of inclusion fluids[J]. Economic Geology,1983,78(3):535-542.
[21] HAAS J L. Physical properties of the coexisting phases and thermochemical properties of the H2O component in boiling Na Cl solutions[J]. U. S. Geological Survey Bulletin,1975,1421-A:1-73.
[22]张振儒,杨思学.金的成色研究[J].地质与勘探,1986,22(11):36-37.
[23]聂凤莲,赵天心,张蜀冀.冀东一些金矿床金矿物特征及金成色地质意义[J].黄金地质,2003,9(1):48-51.
[24]СЕВЕРИНВВ,张维根.自然金成分的不均匀性和不均匀度(可视为自然金的一种标型特征)[J].黄金地质科技,1992(3):72-74.
[25]孟繁聪,孙岱生,寸王圭.胶东金矿金成色及其指示意义[J].黄金地质,1998,4(4):30-32.
[26]陈正,岳树勤,陈殿芬.矿石学上编概论[M].北京:地质出版社,1985:76-82.
[27] POKROVSKI G S,TAGIROV B R,SCHOTT J,et al. A new view on gold speciation in sulfur-bearing hydrothermal fluids from in situ X-ray absorption spectroscopy and quantum-chemical modeling[J]. Geochimica et Cosmochimica Acta,2009,73(18):5406-5427.
[28] PHILLIPS G N,EVANS K A. Role of CO2in the formation of gold deposit[J]. Nature,2004,429:860-863.
[29]黄朋,顾雪祥,唐菊兴.西藏玉龙斑岩铜(钼)矿金属迁移、沉淀机制探讨[J].四川地质学报,2000,20(1):57-61.
[30] GU X X,TANG J X,WANG C S,et al. Himalayan magmatism and porphyry copper-molybdenum mineralization in the Yulong ore belt,East Tibet[J]. Mineralogy and Petrology,2003,78(1/2):1-20.
[31] GUSTAFSON L B,HUNT J P. The porphyry copper deposit at El Salvador,Chile[J]. Economic Geology,1975,70(5):857-912.
[32] HEDENQUIST J W,ARRIBAS A,REYNOLDS T J. Evolution of an intrusion-centered hydrothermal system:Far Southeast-Lepanto porphyry and epithermal Cu-Au deposits,Philippines[J]. Economic Geology,1998,93(4):373-404.
[33]张文淮,张志坚,伍刚.成矿流体及成矿机制[J].地学前缘,1996,3(4):245-252.
[34] ARNRSSON S,STEFNSSON A,BJARNASON J. Fluidfluid interactions in geothermal systems[J]. Reviews in Mineralogy and Geochemistry,2007,65(1):259-312.
[35] MIKUCKI E J. Hydrothermal transport and depositional processes in Archean lode-gold systems:A review[J]. Ore Geology Reviews,1998,13(1):307-321.
[36]陈衍景,倪培,范宏瑞,等.不同类型热液金矿系统的流体包裹体特征[J].岩石学报,2007,23(9):2085-2108.
[2]王刚.内蒙古敖汉旗金厂梁金矿床地球化学特征及成因研究[D].长春:吉林大学,2015:39-41.
[3]孙珍军,李学源,于赫楠,等.内蒙古金厂沟梁金矿床成矿流体特征及稳定同位素研究[J].世界地质,2014,33(3):591-602.
[4]褚金锁,贾洪杰.金厂沟梁金矿床地质特征及成因[J].矿产与地质,2000,14(3):155-158.
[5]侯万荣.内蒙古哈达门沟金矿床与金厂沟梁金矿床对比研究[D].北京:中国地质科学院,2011:157-175.
[6]张长春,王时麒,张韬.内蒙古金厂沟梁金矿床稳定同位素组成和矿床成因讨论[J].地质力学学报,2002,8(2):156-164.
[7]刘宗秀,魏存弟,赵春光,等.金厂沟梁—二道沟金矿田地质地球化学特征及成因探讨[J].世界地质,2002,21(1):13-17.
[8]程裕淇.中国区域地质概论[M].北京:地质出版社,1994:90-163.
[9]王一珅,刘建明,刘红涛,等.内蒙古敖汉旗七家金矿闪长玢岩锆石U-Pb年代学、地球化学及地质意义[J].地质科学,2016,51(2):633-653.
[10]王建平,孟宪刚,杨玉东,等.次火山岩型金矿床构造物理过程研究——以内蒙古金厂沟梁金矿为例[J].地质力学学报,1998,4(2):5-13.
[11] YANG J H,WU F Y,WILDE S A. A review of the geodynamic setting of large-scale late Mesozoic gold mineralization in the North China Craton:an association with lithospheric thinning[J]. Ore Geology Reviews,2003,23(3/4):125-152.
[12]苗来成,范蔚茗,翟明国,等.金厂沟梁—二道沟金矿田内花岗岩类侵入体锆石的离子探针U-Pb年代学及意义[J].岩石学报,2003,19(1):71-80.
[13]王时麒,孙承志,崔文元,等.内蒙古赤峰地区金矿地质[M].呼和浩特:内蒙古人民出版社,1994:138-156.
[14]牛树银,王宝德,张建珍,等.内蒙古金厂沟梁金矿的构造特征及深部找矿预测[J].大地构造与成矿学,2011,35(3):348-354.
[15]段培新,李长民,刘翠,等.内蒙古赤峰金厂沟梁金矿区花岗岩类年代学、地球化学特征及其地质意义[J].岩石学报,2014,30(11):3189-3202.
[16] POTTER R W,CLYNNE M A,BROWN D L. Freezing point depression of aqueous sodium chloride solutions[J]. Economic Geology,1978,73(2):284-285.
[17]刘斌,段光贤. Na Cl-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):345-352.
[18] COLLINS P L F. Gas hydrates in CO2-bearing fluid inclusion and the use of freezing data for estimation of salinity[J]. Economic Geology,1979,74(6):1435-1444.
[19] HALL D L,STERNER S M,BODNAR R J. Freezing point depression of Na Cl-KCl-H2O solutions[J]. Economic Geology,1988,83(1):197-202.
[20] BODNAR R J. A method of calculating fluid inclusion volumes based on vapor bubble diameters and P-V-T-X properties of inclusion fluids[J]. Economic Geology,1983,78(3):535-542.
[21] HAAS J L. Physical properties of the coexisting phases and thermochemical properties of the H2O component in boiling Na Cl solutions[J]. U. S. Geological Survey Bulletin,1975,1421-A:1-73.
[22]张振儒,杨思学.金的成色研究[J].地质与勘探,1986,22(11):36-37.
[23]聂凤莲,赵天心,张蜀冀.冀东一些金矿床金矿物特征及金成色地质意义[J].黄金地质,2003,9(1):48-51.
[24]СЕВЕРИНВВ,张维根.自然金成分的不均匀性和不均匀度(可视为自然金的一种标型特征)[J].黄金地质科技,1992(3):72-74.
[25]孟繁聪,孙岱生,寸王圭.胶东金矿金成色及其指示意义[J].黄金地质,1998,4(4):30-32.
[26]陈正,岳树勤,陈殿芬.矿石学上编概论[M].北京:地质出版社,1985:76-82.
[27] POKROVSKI G S,TAGIROV B R,SCHOTT J,et al. A new view on gold speciation in sulfur-bearing hydrothermal fluids from in situ X-ray absorption spectroscopy and quantum-chemical modeling[J]. Geochimica et Cosmochimica Acta,2009,73(18):5406-5427.
[28] PHILLIPS G N,EVANS K A. Role of CO2in the formation of gold deposit[J]. Nature,2004,429:860-863.
[29]黄朋,顾雪祥,唐菊兴.西藏玉龙斑岩铜(钼)矿金属迁移、沉淀机制探讨[J].四川地质学报,2000,20(1):57-61.
[30] GU X X,TANG J X,WANG C S,et al. Himalayan magmatism and porphyry copper-molybdenum mineralization in the Yulong ore belt,East Tibet[J]. Mineralogy and Petrology,2003,78(1/2):1-20.
[31] GUSTAFSON L B,HUNT J P. The porphyry copper deposit at El Salvador,Chile[J]. Economic Geology,1975,70(5):857-912.
[32] HEDENQUIST J W,ARRIBAS A,REYNOLDS T J. Evolution of an intrusion-centered hydrothermal system:Far Southeast-Lepanto porphyry and epithermal Cu-Au deposits,Philippines[J]. Economic Geology,1998,93(4):373-404.
[33]张文淮,张志坚,伍刚.成矿流体及成矿机制[J].地学前缘,1996,3(4):245-252.
[34] ARNRSSON S,STEFNSSON A,BJARNASON J. Fluidfluid interactions in geothermal systems[J]. Reviews in Mineralogy and Geochemistry,2007,65(1):259-312.
[35] MIKUCKI E J. Hydrothermal transport and depositional processes in Archean lode-gold systems:A review[J]. Ore Geology Reviews,1998,13(1):307-321.
[36]陈衍景,倪培,范宏瑞,等.不同类型热液金矿系统的流体包裹体特征[J].岩石学报,2007,23(9):2085-2108.