南岭钨矿“五层楼模式”的结构与构式——以粤北始兴县梅子窝钨矿为例
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摘要
南岭脉状钨矿的"五层楼模式",在纵剖面上具正扇形结构,横剖面上具树形分叉结构,平面上沿构造带呈定向脉组(群)分布。从上往下,矿脉分布的分维值(平均1.10)从大变小。认为燕山期含矿岩浆流体沿构造带发生定向的周期性地震泵吸、液压致裂与裂开-愈合。对于同一条矿脉,矿脉的扩展速率与扩展时间决定了脉幅的大小:脉幅越大,扩展速率就越小,扩展时间就越长,起始时间也就越早;而脉幅越小,扩展速率也就越大,扩展时间就越短,起始时间也就越晚。认为脉的扩展速率与液压、围压的相对大小有关:当液压一定时,围压越大,则脉的扩展速率就越小;而围压越小,脉的扩展速率就越大。由于各处围压及扩展时间长短的差异,"五层楼"模式中的中部、深部、侧部、上部的矿脉构式、脉幅具有明显的差异:中部单脉出现分支复合,脉幅稳定;侧部单脉出现自然尖灭或单侧分支尖灭、双则分支尖灭;上部则出现复杂的树形分支,分支自然尖灭或分支与分支之间的复合尖灭,深部可能为自然尖灭。
The "five-storeyed type" model of the vein-type tungsten deposits in the Nanling Mountains,Southern China,has a normal sector texture on the lengthwise section,a branch-like texture on cross profile,and is distributed along along structural belts in oriented vein groups.With the increase of depth,the fractal dimension of the veins(averaging 1.10) in the Meiziwo tungsten Deposit,Shixing County,decreases gradually.Oriented and periodical earthquake-pumping,hydrofracturing and rupture-healing occurred when the ore-bearing fluid from Yanshanian magma moved along the structural belts..For the same ore vein,the breadth of the vein is determined by its dilation rate and time: the bigger the breadth is the much smaller its dilation rate is,and much longer dilation time is needed and and its starting time is much earlier;or vice versa.The study suggests that the dilation rate has close relation to the relative size between hydraulic pressure and confining pressure: if the hydraulic pressure is given,the larger the confining pressure is,the smaller the dilation rate,or vice versa.The differences of confining pressures and dilation rates here and there make the tectonic styles and the breadth obviously different from each other in the central section,the bottom section,the side section and the top section in the "five-storeyed type".Individual vein in the central section is characterized by continuous composite veins with stable breadth;individual veins in the lateral sections wedges out naturally,or its swithers pinching out either at one side or both sides;complicated treelike swithers appear at the top section with swithers pinching out naturally or composite between swithers pinching out by inches;while at the bottom section,the veins are likely to wedge out naturally.
The "five-storeyed type" model of the vein-type tungsten deposits in the Nanling Mountains,Southern China,has a normal sector texture on the lengthwise section,a branch-like texture on cross profile,and is distributed along along structural belts in oriented vein groups.With the increase of depth,the fractal dimension of the veins(averaging 1.10) in the Meiziwo tungsten Deposit,Shixing County,decreases gradually.Oriented and periodical earthquake-pumping,hydrofracturing and rupture-healing occurred when the ore-bearing fluid from Yanshanian magma moved along the structural belts..For the same ore vein,the breadth of the vein is determined by its dilation rate and time: the bigger the breadth is the much smaller its dilation rate is,and much longer dilation time is needed and and its starting time is much earlier;or vice versa.The study suggests that the dilation rate has close relation to the relative size between hydraulic pressure and confining pressure: if the hydraulic pressure is given,the larger the confining pressure is,the smaller the dilation rate,or vice versa.The differences of confining pressures and dilation rates here and there make the tectonic styles and the breadth obviously different from each other in the central section,the bottom section,the side section and the top section in the "five-storeyed type".Individual vein in the central section is characterized by continuous composite veins with stable breadth;individual veins in the lateral sections wedges out naturally,or its swithers pinching out either at one side or both sides;complicated treelike swithers appear at the top section with swithers pinching out naturally or composite between swithers pinching out by inches;while at the bottom section,the veins are likely to wedge out naturally.
引文
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何绍勋,奚小双.1988.对江西西华山钨矿脉雁列构造成因的初步探讨.地质学报,62(1):31~42.
柳志青.1980.脉状钨矿床成矿预测理论.北京:科学出版社.
刘科,王景明.2005.河北平原构造特征、地裂缝分布及成因机制.南水北调与水利科技,3(6):38~42.
彭恩生,孙振家.1994.脉状矿床成矿构造研究.长沙:中南大学出版社.
宋鸿林.1996.斜向滑动与走滑转换构造.地质科技情报,15(4):33~38.
孙凡臣,丁国瑜.1991.线性构造分数维值含义.地震,(5):33~37.
汪劲草,汤静如,王国富,史静海.2001.太白双王含金水压角砾岩体形成过程和金矿体预测.地质论评,47(5):508~513.
汪劲草,王蓉嵘,周瑶,万方良,陈彬彬.2006.矿体的侧伏规律及其地质意义.桂林工学院学报,26(3):305~309.
汪劲草,夏斌,嵇少丞.2003.论构造透镜体控矿.中国科学,33(8):745~750.
杨明桂.1989.论成矿预测中的控矿构造型式研究.江西地质,3(3):256~274.
易顺华,李同林,李珍.1994.热液脉动与岩浆涌动控制机制浅论.地质科技情报,13(1):86~88.
章雨旭.1987.长营岭钨锡矿床中黑钨矿锡石石英脉成因探讨.中国地质科学院地质研究所所刊,第17号.北京:地质出版社,75~84.
曾庆丰.1986.论热液成矿条件.北京:北京科技出版社.
Cowie P A,Knipe RJ,Main I G,Wojtal S F.1996.Scaling lawsfor fault andfracture populations:Analyses and applications.J.Struct.Geol.,18:135~383.
Cox S F,1995.Faulting process at highfluid pressures;an exampleof fault valve behavior from the Wattle Gully Fault,Vitoria,Autralia.J.Geophys.Res,100(B7):12841~12859.
Fyfe W S,1986.Fluids,tectonics and crustal deformation.Tectonophysics,119:29~36.
Fyfe WS.1987.Tectonics,fluids and ore deposits:mobilization andremobilization.Ore Geol.Rev.,2:21~36
Phillips W J.1972.Hydraulic fracturing and mineralization.J.Geol.Soc.,128:337~359.
Sibson R H,Moore J M,Rainkin A H.1975.Seismic pumping---a hydrothermal fluidtransport mechanism.J.Geol.Soc.,231:653~659.
Sibson R H.1989.Earthquake faulting as a structural process.J.Geol.Soc,11:1~14.
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