中国云南金顶铅锌矿碎屑灌入体和水力压裂构造的观察及流体动力学分析
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摘要
金顶铅锌矿曾被认为是形成于相对被动地受构造与沉积相控制的盆地流体,类似于许多其他沉积岩容矿的金属矿床。然而,一些近期研究显示在金顶矿区露天采场存在砂岩灌入体、侵位角砾岩和水力压裂构造,说明矿床可能形成于超压流体的爆发性释放。文中报道在地下坑道(跑马坪和峰子山)中新观察到的与超压流体有关的构造,这些构造显示比露天采场有更清楚的交切关系。所观察到的构造包括:(1)灌入固结岩石缝隙的砂岩(±岩石碎块)岩墙;(2)侵入松散或半固结沉积物中的砂岩(±岩石碎块)体;(3)裂散的半固结砂岩体;(4)固结岩石受水力压裂作用然后被热液矿物胶结而形成的角砾岩和岩脉。砂岩灌入体和水力压裂构造中矿石矿物(闪锌矿)胶结物的发育表明,这些构造的形成时代与矿化时代相同。多向水力压裂和角砾岩的发育表明矿化过程中应力差很小,这与矿化前强烈的水平挤压构造应力场不同。根据砂岩岩墙中碎屑大小计算出来的流体流速可能高达11m/s。碎屑灌入体和水力压裂构造可能形成于超高压流体的爆发性释放,这可能和深部岩浆侵入或地震活动有关。这些活动周期性地打开了深部的高压流体库。由于碎屑灌入体和水力压裂构造与成矿流体的来源紧密联系在一起,它们与成矿作用密切相关,可以用作成矿指示。
The Jinding Zn-Pb deposit has been generally considered to have formed from circulating basinal fluids in a relatively passive way,with fluid flow being controlled by structures and sedimentary facies,similar to many other sediments-hosted base metal deposits.However,several recent studies revealed the presence of sand injection structures,intrusive breccias,and hydraulic fractures in the open pit of the Jinding deposit and suggested that the deposit was formed from explosive release of overpressured fluids.This study reports new observations of fluid overpressure related structures from underground workings(Paomaping and Fengzishan),which show clearer crosscutting relationships than in the open pit.The observed structures include:(1) sand(± rock fragment) dikes injecting into fractures in solidified rocks;(2) sand(± rock fragment) bodies intruding into unconsolidated or semi-consolidated sediments;(3) disintegrated semi-consolidated sand bodies;and(4) veins and breccias formed from hydraulic fracturing of solidified rocks followed by cementation of hydrothermal minerals.The development of ore minerals(sphalerite) in the cement of the various clastic injection and hydraulic fractures indicate that these structures were formed at the same time as mineralization.The development of hydraulic fractures and breccias with random orientation indicates small differential stress during mineralization,which is different from the stress field with strong horizontal shortening prior to mineralization.Fluid flow velocity may have been up to more than 11 m/second based on calculations from the size of the fragments in the clastic dikes.The clastic injection and hydraulic fracturing structures are interpreted to have formed from explosive release of overpressured fluids,which may have been related to either magmatic intrusions at depth or seismic activities which episodically tapped an overpressured fluid reservoir.Because the clastic injection and hydraulic structures are genetically linked with the mineralizing fluid source,they can be used as a guide for mineral exploration.
The Jinding Zn-Pb deposit has been generally considered to have formed from circulating basinal fluids in a relatively passive way,with fluid flow being controlled by structures and sedimentary facies,similar to many other sediments-hosted base metal deposits.However,several recent studies revealed the presence of sand injection structures,intrusive breccias,and hydraulic fractures in the open pit of the Jinding deposit and suggested that the deposit was formed from explosive release of overpressured fluids.This study reports new observations of fluid overpressure related structures from underground workings(Paomaping and Fengzishan),which show clearer crosscutting relationships than in the open pit.The observed structures include:(1) sand(± rock fragment) dikes injecting into fractures in solidified rocks;(2) sand(± rock fragment) bodies intruding into unconsolidated or semi-consolidated sediments;(3) disintegrated semi-consolidated sand bodies;and(4) veins and breccias formed from hydraulic fracturing of solidified rocks followed by cementation of hydrothermal minerals.The development of ore minerals(sphalerite) in the cement of the various clastic injection and hydraulic fractures indicate that these structures were formed at the same time as mineralization.The development of hydraulic fractures and breccias with random orientation indicates small differential stress during mineralization,which is different from the stress field with strong horizontal shortening prior to mineralization.Fluid flow velocity may have been up to more than 11 m/second based on calculations from the size of the fragments in the clastic dikes.The clastic injection and hydraulic fracturing structures are interpreted to have formed from explosive release of overpressured fluids,which may have been related to either magmatic intrusions at depth or seismic activities which episodically tapped an overpressured fluid reservoir.Because the clastic injection and hydraulic structures are genetically linked with the mineralizing fluid source,they can be used as a guide for mineral exploration.
引文
[1]孙勇,许绍倬.云南金顶铅锌矿床成矿溶液运移通道的古水文地质分析[J].地球科学:中国地质大学学报,1989,14(5):487-494.
[2]覃功炯,朱上庆.金顶铅锌矿床成因模式及找矿预测[J].云南地质,1991,10(2):145-190.
[3]Li N.Depositional Controls and Genesis of the Jinding Sand-stone-Hosted Zn-Pb Deposit,Yunnan Province,SouthwestChina[D].Austin:University of Texas,1998:236.
[4]Kyle J K,Li N.Jinding:A Giant Tertiary sandstone-hostedZn-Pb deposit,Yunnan,China[J].Society of Economic Ge-ologists Newsletter,2002,50:8-16.
[5]徐启东,李建威.云南兰坪北部铜多金属矿化区成矿流体流动与矿化分带:流体包裹体和稳定同位素依据[J].矿床地质,2003,22(4):365-376.
[6]王江海,颜文,常向阳,等.陆相热水沉积作用:以云南地区为例[M].北京:地质出版社,1998:134.
[7]高兰,王安建,刘俊来,等.滇西北兰坪金顶超大型矿床研究新进展:侵位角砾岩的发现及其地质意义[J].矿床地质,2005,24(4):457-461.
[8]王安建,高兰,刘俊来,等.论兰坪金顶超大型铅锌矿容矿角砾岩的成因[J].地质学报,2007,81(7):891-911.
[9]高广立.论金顶铅锌矿床的地质问题[J].地球科学:中国地质大学学报,1989,14(5):468-475.
[10]Chi G X,Qing H R,Xue C J,et al.An overpressured fluidsystem associated with the giant sandstone-hosted JindingZn-Pb deposit,western Yunnan,China[M]∥Mao J,BierleinF P.Mineral Deposit Research:Meeting the Global Chal-lenge.Berlin/Heidelberg:Springer-Verlag,2005:93-96.
[11]Chi G X,Qing H R,Xue C J,et al.Modeling of fluid pres-sure evolution related to sediment loading and thrust faultingin the Lanping basin:Implications for the formation of theJinding Zn-Pb deposit,Yunnan,China[J].Journal of Geo-chemical Exploration,2006,89:57-60.
[12]尹汉辉,范蔚茗,林舸.云南兰坪-思茅地洼盆地演化的深部因素及幔-壳复合成矿作用[J].大地构造与成矿学,1990,14(2):113-124.
[13]Chi G X,Xue C J,Lai J Q,et al.Sand injection and liquefac-tion structures in the Jinding Zn-Pb deposit,Yunnan,China:Indicators of an overpressured fluid system and implicationsfor mineralization.Economic Geology,2007,102:739-743.
[14]Xue C J,Chen Y C,Wang D H,et al.Geology and isotopiccomposition of helium,neon,xenon and metallogenic age ofthe Jinding and Baiyangping ore deposits,northwest Yunnan,China[J].Science in China:Series D,2003,46:789-800.
[15]吕伯西,钱祥贵.滇西新生代碱性火山岩、富碱斑岩深源包体岩石学研究[J].云南地质,1999,18(2):127-143.
[16]张成江,倪师军,腾彦国,等.兰坪盆地喜马拉雅期构造-岩浆活动与流体成矿的关系[J].矿物岩石,2000,20(2):35-39.
[17]云南地质矿产局第三地质队.云南省兰坪县金顶铅锌矿床勘探报告[R].昆明:云南地质矿产局,1984:449.
[18]Xue C J,Zeng R,Liu S W,et al.Geologic,fluid inclusionand isotopic characteristics of the Jinding Zn-Pb deposit,western Yunnan,South China:A review[J].Ore GeologyReviews,2007,31:337-359.
[19]Hubbert M K,Willis D G.Mechanics of hydraulic fracturing[J].Transactions of the American Institute of Mining,Met-allurgical,and Petroleum Engineers,1957,210:153-166.
[20]Phillips W J.Hydraulic fracturing and mineralization[J].Journal of Geological Society,London,1972,128:337-359.
[21]Ramsay J G.Folding and Fracturing of Rocks[M].NewYork:McGraw-Hill,1967:560.
[22]Guha J,Archambault G,Leroy J.A correlation between theevolution of mineralizing fluids and the geomechanical devel-opment of a shear zone as illustrated by the Henderson 2Mine,Quebec[J].Economic Geology,1983,78:1605-1618.
[23]Hodgson C J.The structure of shear-related,vein-type gold de-posits:A review[J].Ore Geology Review,1989,4:231-273.
[24]Jolly R J H,Lonergan L.Mechanisms and controls on theformation of sand intrusions[J].Journal of the Geological So-ciety,London,2002,159:605-617.
[25]Delaney P T,Pollard D D,Ziony J I,et al,Field relationsbetween dikes and joints:Emplacement processes and pal-eostress analysis[J].Journal of Geophysical Research,1986,91:4920-4938.
[26]Richardson J F.Incipient fluidization and particulate systems[M]∥Davidson J F,Harrison D.Fluidization.London:Ac-ademic Press,1971:25-64.
[27]Likhachev E R.Dependence of water viscosity on tempera-ture and pressure[J].Technical Physics,2003,48:514-515.
[28]Sillitoe R H.Ore-related breccias in volcanoplutonic arcs[J].Economic Geology,1985,80:1467-1514.
[29]Bryant D G.Intrusive breccias associated with ore,Warren(Bisbee)mining district,Arizona[J].Economic Geology,1968,63:1-12.
[30]王京彬,李朝阳,陈晓钟.金顶铅锌矿床成因新说[J].有色金属矿产与勘查,1992,1(4):200-206.
[31]Xue C J,Wang D H,Chen Y C,et al.Helium,argon,andxenon isotopic compositions of ore-forming fluids in Jinding-Baiyangping polymetallic deposits,Yunnan,Southwest China[J].Acta Geologica Sinica,2000,74:521-528.
[32]Shi J X,Yi F H,Wen Q H.Petrographic characteristics ofores and host rocks and genesis of the Jinding Pb-Zn deposit,Lanping[J].Journal of Yunnan Geology,1983,2:179-193.
[2]覃功炯,朱上庆.金顶铅锌矿床成因模式及找矿预测[J].云南地质,1991,10(2):145-190.
[3]Li N.Depositional Controls and Genesis of the Jinding Sand-stone-Hosted Zn-Pb Deposit,Yunnan Province,SouthwestChina[D].Austin:University of Texas,1998:236.
[4]Kyle J K,Li N.Jinding:A Giant Tertiary sandstone-hostedZn-Pb deposit,Yunnan,China[J].Society of Economic Ge-ologists Newsletter,2002,50:8-16.
[5]徐启东,李建威.云南兰坪北部铜多金属矿化区成矿流体流动与矿化分带:流体包裹体和稳定同位素依据[J].矿床地质,2003,22(4):365-376.
[6]王江海,颜文,常向阳,等.陆相热水沉积作用:以云南地区为例[M].北京:地质出版社,1998:134.
[7]高兰,王安建,刘俊来,等.滇西北兰坪金顶超大型矿床研究新进展:侵位角砾岩的发现及其地质意义[J].矿床地质,2005,24(4):457-461.
[8]王安建,高兰,刘俊来,等.论兰坪金顶超大型铅锌矿容矿角砾岩的成因[J].地质学报,2007,81(7):891-911.
[9]高广立.论金顶铅锌矿床的地质问题[J].地球科学:中国地质大学学报,1989,14(5):468-475.
[10]Chi G X,Qing H R,Xue C J,et al.An overpressured fluidsystem associated with the giant sandstone-hosted JindingZn-Pb deposit,western Yunnan,China[M]∥Mao J,BierleinF P.Mineral Deposit Research:Meeting the Global Chal-lenge.Berlin/Heidelberg:Springer-Verlag,2005:93-96.
[11]Chi G X,Qing H R,Xue C J,et al.Modeling of fluid pres-sure evolution related to sediment loading and thrust faultingin the Lanping basin:Implications for the formation of theJinding Zn-Pb deposit,Yunnan,China[J].Journal of Geo-chemical Exploration,2006,89:57-60.
[12]尹汉辉,范蔚茗,林舸.云南兰坪-思茅地洼盆地演化的深部因素及幔-壳复合成矿作用[J].大地构造与成矿学,1990,14(2):113-124.
[13]Chi G X,Xue C J,Lai J Q,et al.Sand injection and liquefac-tion structures in the Jinding Zn-Pb deposit,Yunnan,China:Indicators of an overpressured fluid system and implicationsfor mineralization.Economic Geology,2007,102:739-743.
[14]Xue C J,Chen Y C,Wang D H,et al.Geology and isotopiccomposition of helium,neon,xenon and metallogenic age ofthe Jinding and Baiyangping ore deposits,northwest Yunnan,China[J].Science in China:Series D,2003,46:789-800.
[15]吕伯西,钱祥贵.滇西新生代碱性火山岩、富碱斑岩深源包体岩石学研究[J].云南地质,1999,18(2):127-143.
[16]张成江,倪师军,腾彦国,等.兰坪盆地喜马拉雅期构造-岩浆活动与流体成矿的关系[J].矿物岩石,2000,20(2):35-39.
[17]云南地质矿产局第三地质队.云南省兰坪县金顶铅锌矿床勘探报告[R].昆明:云南地质矿产局,1984:449.
[18]Xue C J,Zeng R,Liu S W,et al.Geologic,fluid inclusionand isotopic characteristics of the Jinding Zn-Pb deposit,western Yunnan,South China:A review[J].Ore GeologyReviews,2007,31:337-359.
[19]Hubbert M K,Willis D G.Mechanics of hydraulic fracturing[J].Transactions of the American Institute of Mining,Met-allurgical,and Petroleum Engineers,1957,210:153-166.
[20]Phillips W J.Hydraulic fracturing and mineralization[J].Journal of Geological Society,London,1972,128:337-359.
[21]Ramsay J G.Folding and Fracturing of Rocks[M].NewYork:McGraw-Hill,1967:560.
[22]Guha J,Archambault G,Leroy J.A correlation between theevolution of mineralizing fluids and the geomechanical devel-opment of a shear zone as illustrated by the Henderson 2Mine,Quebec[J].Economic Geology,1983,78:1605-1618.
[23]Hodgson C J.The structure of shear-related,vein-type gold de-posits:A review[J].Ore Geology Review,1989,4:231-273.
[24]Jolly R J H,Lonergan L.Mechanisms and controls on theformation of sand intrusions[J].Journal of the Geological So-ciety,London,2002,159:605-617.
[25]Delaney P T,Pollard D D,Ziony J I,et al,Field relationsbetween dikes and joints:Emplacement processes and pal-eostress analysis[J].Journal of Geophysical Research,1986,91:4920-4938.
[26]Richardson J F.Incipient fluidization and particulate systems[M]∥Davidson J F,Harrison D.Fluidization.London:Ac-ademic Press,1971:25-64.
[27]Likhachev E R.Dependence of water viscosity on tempera-ture and pressure[J].Technical Physics,2003,48:514-515.
[28]Sillitoe R H.Ore-related breccias in volcanoplutonic arcs[J].Economic Geology,1985,80:1467-1514.
[29]Bryant D G.Intrusive breccias associated with ore,Warren(Bisbee)mining district,Arizona[J].Economic Geology,1968,63:1-12.
[30]王京彬,李朝阳,陈晓钟.金顶铅锌矿床成因新说[J].有色金属矿产与勘查,1992,1(4):200-206.
[31]Xue C J,Wang D H,Chen Y C,et al.Helium,argon,andxenon isotopic compositions of ore-forming fluids in Jinding-Baiyangping polymetallic deposits,Yunnan,Southwest China[J].Acta Geologica Sinica,2000,74:521-528.
[32]Shi J X,Yi F H,Wen Q H.Petrographic characteristics ofores and host rocks and genesis of the Jinding Pb-Zn deposit,Lanping[J].Journal of Yunnan Geology,1983,2:179-193.
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