广西六琼矿区热泉型金矿床网脉-角砾岩特征及其成因探讨
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摘要
六琼金矿区内有Ⅰ、Ⅱ、Ⅲ号3个热泉型含金矿化体,在平面上均呈透镜状,产于断裂带附近并沿断裂走向断续分布,矿化体内岩石为流体动力角砾岩。按蚀变类型不同,矿区内流体动力角砾岩可分为2个系列:铁系列和硅系列的流化角砾岩和液压角砾岩。组成热泉构造的网脉-角砾岩系具有明显的构造分带性,从中心向两侧依次为:管道相流化角砾岩→中间相液压角砾岩→边缘相初液压角砾岩和网脉状矿化体→正常围岩。褐铁矿矿化强度由管道相向边缘相逐渐减弱,金矿化在管道相内不发育,在中间相和边缘相发育较好,由中间相向边缘相金矿化逐渐减弱。控泉断裂受地震脉动机制释放应力控制;热泉构造受构造泵吸和液压致裂作用控制,多次构造-流体事件产生的裂开-愈合作用形成了具有构造分带的网脉-角砾岩系的热泉型成矿构造。
The Liuqiong hot spring type gold deposit consists of three lenticular orebodies(No.I,No.II,and No.III)existing in proximity to the faults zone and trace the surface trend of the faults.Gold ores are largely composed of fluid dynamic breccias that,in light of the alteration and hydrothermal cements,fall into 2 types: fluidized breccias and hydrofracturing breccias of iron series and silicon series.The stockwork and breccias display excellent planer zonation,marked by fluidized breccias in the center,hydrofracturing breccias in the transitional zone,and incipient hydrofracturing breccias in the marginal area.Limonite is most intensely developed in the center of the breccia-vein system,whereas strongest gold mineralization is observed in the transitional and marginal zones,with the central part lack of gold.The vein-breccias are interpreted to be controlled by the mechanism of earthquake pumping acting in the faults and hydraulic fracturing in the extensional segments of the faults driven by overpressurized fluids.The episodic faulting and hydraulic fracturing resulted in repeated cracking-sealing of the veins that cement the breccias,forming the zonation of the breccia-vein system.
The Liuqiong hot spring type gold deposit consists of three lenticular orebodies(No.I,No.II,and No.III)existing in proximity to the faults zone and trace the surface trend of the faults.Gold ores are largely composed of fluid dynamic breccias that,in light of the alteration and hydrothermal cements,fall into 2 types: fluidized breccias and hydrofracturing breccias of iron series and silicon series.The stockwork and breccias display excellent planer zonation,marked by fluidized breccias in the center,hydrofracturing breccias in the transitional zone,and incipient hydrofracturing breccias in the marginal area.Limonite is most intensely developed in the center of the breccia-vein system,whereas strongest gold mineralization is observed in the transitional and marginal zones,with the central part lack of gold.The vein-breccias are interpreted to be controlled by the mechanism of earthquake pumping acting in the faults and hydraulic fracturing in the extensional segments of the faults driven by overpressurized fluids.The episodic faulting and hydraulic fracturing resulted in repeated cracking-sealing of the veins that cement the breccias,forming the zonation of the breccia-vein system.
引文
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[2]Nelson C E,G iles D L.Hydrothermal eruption mechanismsand hot spring gold deposits[J].Econom ic Geology,1985,80(8):1633-1639.
[3]郭光裕,候宗林.热泉型金矿床成矿模式及成矿远景评价[M].天津:天津科学技术出版社,1993:1-10.
[4]郭福详.广西大地构造单元[J].桂林冶金地质学院学报,1994,14(3):233-243.
[5]汪劲草,彭恩生,孙振家.流体动力角砾岩分类及其地质意义[J].长春科技大学学报,2000,30(1):18-23.
[6]汪劲草,汤静如,王国富,等.太白双王含金水压角砾岩体的形成过程与金矿体预测[J].地质论评,2001,7(5):508-513.
[7]翟裕生.矿田构造学概论[M].北京:冶金工业出版社,1984:58-87.
[8]Cowie P A,Knipe R J,Main I G,et al.Scaling laws for faultand fracture populations:Analyses and applications[J].Jour-nal of Structural Geology,1996,18(2):135-383.
[9]李建威,李先福.液压致裂作用及其研究意义[J].地质科技情报,1997,16(4):21-34.
[10]赵伦山,岑况,叶荣.热液流体泵吸上侵管流动力学模拟及其预测意义[J].地学前缘,2000,7(1):205-214.
[11]Cox S F.Faulting process at high fluid pressures:an exam-ple of fault valve behavior from theW attle Gully Fault,V ito-ria,Aut ralia[J].Journal ofGeophysics Research,1995,100(B7):12841-12859.
[12]Meere P A.H igh and low density fluids in a quarts vein fromthe Irish Variscides[J].Journal of Structural Geology,1995,17(3):435-446.
[13]汪劲草,王建业,王正云,等.东天山达坂城大规模层间水压碎屑岩的发现及意义[J].桂林工学院学报,1998,18(2):104-111.
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