安徽庐枞盆地井边地区脉状铜矿成矿流体特征与成矿过程研究
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摘要
庐枞盆地是长江中下游成矿带重要的矿集区之一,盆地内发育众多脉状铜矿床(点)。文章以井边地区的张家店铜矿、井边铜矿、周洼铜矿和虎栈铜矿为研究对象,分析井边地区脉状铜矿成矿流体特征,探讨脉状铜矿的成矿机制。研究表明:该区流体包裹体主要为气液两相包裹体,偶见纯液相包裹体和纯气相包裹体,流体系统为H2O-NaCl型。流体包裹体显微测温结果显示,成矿流体具有中温(220~240℃)、中低盐度(8wt%~20wt%)、低密度(0.86~1.16g/cm~3)的特征,流体体系沸腾作用不强。岩浆热液与大气降水的混合作用使成矿物质在岩体及围岩裂隙中析出、沉淀并富集成矿,形成受断裂控制的脉状铜矿床。
The Lujiang-Zongyang volcanic basin in Anhui Province is one of the important ore cluster regions in the Middle-Lower Yangtze metallogenic belt,which hosts many vein-type copper deposits(points).In this study,four vein-type copper deposits at Zhangjiadian,Jingbian,Zhouwa and Huzhan in the Jingbian area were chosen to study the characteristics of ore-forming fluids in order to preliminarily understand the metallogenic mechanism of vein type copper deposits.The study shows that fluid inclusions in the deposits are dominated by two-phase gas-liquid inclusions,occasionally with gaseous inclusions and pure liquid inclusions,suggesting that fluid system belongs to a H2 O-NaCl system.The microthermomentric analyses of the fluid inclusions show that the ore-forming fluids are characterized by mediumtemperature(220~240 ℃),low-medium salinity(8 wt% ~20 wt%)and low density(0.86~1.16 g/cm3),indicating that the ore-forming fluid experienced weak fluid-boiling.It can be concluded that mixing between magmatic water and meteoric water resulted in extraction,precipitation and enrichment of the oreforming materials in the fractures of rock mass and country rocks,thus forming fault-controlled vein-type copper deposits.
The Lujiang-Zongyang volcanic basin in Anhui Province is one of the important ore cluster regions in the Middle-Lower Yangtze metallogenic belt,which hosts many vein-type copper deposits(points).In this study,four vein-type copper deposits at Zhangjiadian,Jingbian,Zhouwa and Huzhan in the Jingbian area were chosen to study the characteristics of ore-forming fluids in order to preliminarily understand the metallogenic mechanism of vein type copper deposits.The study shows that fluid inclusions in the deposits are dominated by two-phase gas-liquid inclusions,occasionally with gaseous inclusions and pure liquid inclusions,suggesting that fluid system belongs to a H2 O-NaCl system.The microthermomentric analyses of the fluid inclusions show that the ore-forming fluids are characterized by mediumtemperature(220~240 ℃),low-medium salinity(8 wt% ~20 wt%)and low density(0.86~1.16 g/cm3),indicating that the ore-forming fluid experienced weak fluid-boiling.It can be concluded that mixing between magmatic water and meteoric water resulted in extraction,precipitation and enrichment of the oreforming materials in the fractures of rock mass and country rocks,thus forming fault-controlled vein-type copper deposits.
引文
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[26]杜玉雕,刘家军,余心起,等.安徽逍遥钨多金属矿床成矿物质来源与成矿:碳、硫和铅同位素证据[J].中国地质,2013,40(2):566-579.
[27]张德会.流体的沸腾和混合在热液成矿中的意义[J].地球科学进展,1997,12(6):546-552.
[28]卢焕章,单强.金属矿床的成矿流体成分和流体包裹体[J].岩石学报,2015,31(4):1108-1116.
[29]周涛发,范裕,袁峰,等.安徽庐枞盆地泥河铁矿床与膏盐层的成因联系及矿床成矿模式[J].地质学报,2014,88(4):562-573.
[30]左晓敏,杜杨松,曹毅,等.安徽桂花冲铜矿床成矿流体演化特征研究[J].矿床地质,2016,35(1):117-129.
[31]周小栋.宁芜北部脉状铜矿床成因及成矿机制研究[D].合肥:合肥工业大学,2013:1-74.
[2]赵文广,吴明安,张宜勇,等.安徽省庐江县泥河铁硫矿床地质特征及成因初步分析[J].地质学报,2011,85(5):789-802.
[3]吴明安,汪青宋,郑光文,等.安徽庐江泥河铁矿的发现及意义[J].地质学报,2011,85(5):802-809.
[4]覃永军.安徽庐枞盆地燕山期成矿地球动力学背景及成矿模式[D].武汉:中国地质大学(武汉),2010:1-149.
[5]汤家富,陆三明,李建设,等.安徽庐枞火山岩盆地与邻区基底构造变形、形成演化及其对矿床分布的控制[J].岩石学报,2010,26(9):2587-2597.
[6]张乐骏.安徽庐枞盆地成岩成矿作用研究[D].合肥:合肥工业大学,2011:1-239.
[7]袁峰,周涛发,范裕,等.庐纵盆地中生代火山岩的起源、演化及形成背景[J].岩石学报,2008,24(10):1691-1702.
[8]周涛发,范裕,袁峰,等.长江中下游成矿带火山岩盆地的成岩成矿作用[J].地质学报,2011,85(5):712-730.
[9]周涛发,范裕,袁峰,等.庐枞盆地侵入岩的时空格架及其对成矿的制约[J].岩石学报,2010,26(9):2694-2714.
[10]周涛发,范裕,袁峰.长江中下游成矿带成岩成矿作用研究进展[J].岩石学报,2008,24(8):1665-1678.
[11]张乐骏,周涛发,范裕,等.安徽庐枞盆地井边铜矿床的成矿时代及其找矿指示意义[J].岩石学报,2010,26(9):2729-2738.
[12]覃永军,曾键年,王思源,等.安徽庐枞盆地井边铜(金)矿床成矿特征及控矿地质因素探讨[J].矿床地质,2010,29(5):915-930.
[13]张靖怡,张赞赞,郑光文,等.安徽庐枞盆地杀虎台铜矿床成矿流体特征研究[J].安徽地质,2017,27(1):29-32.
[14]徐兆文,任启江,杨荣勇,等.安徽庐枞地区脉状铜矿、铜金矿化分布规律和矿床模式[J].地质与勘探,1992,28(1):8-15.
[15]李玉松,蔡晓兵,汪晶,等.安徽庐枞盆地黄寅冲铅锌矿床闪长玢岩锆石U-Pb年龄及其地质意义[J].华东地质,2016,37(1):19-27.
[16]张舒,吴明安,汪晶,等.安徽庐枞盆地与正长岩有关的成矿作用[J].地质学报,2014,88(4):519-531.
[17]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.
[18]张文淮,陈紫英.流体包裹体地质学[M].武汉:中国地质大学出版社,1993:1-246.
[19]石磊.安徽庐枞地区铜(金)矿床地质地球化学特征及成因[D].合肥:合肥工业大学,2011:1-60.
[20]刘斌,沈昆.流体包裹体热力学[M].北京:地质出版社,1999:31-277.
[21]卢焕章,范洪瑞,倪培,等.流体包裹体[M].北京:科学出版社,2004:207.
[22]Shepherd T J,RakinA,Alderton D H M.A practical guide to fluid inclusion studies[M].Glasgow:Blackie Academic&Professional,1985:1-154.
[23]郑永飞,陈江峰.稳定同位素地球化学[M].北京:科学出版社,2000:1-316.
[24]周龙全,李光来,唐傲,等.赣南地区石英脉型钨矿成矿流体特征[J].华东地质,2016,37(2):136-146.
[25]杜玉雕,余心起,刘家军,等.皖南东源钨钼矿成矿流体特征和成矿物质来源[J].中国地质,2011,38(5):1334-1346.
[26]杜玉雕,刘家军,余心起,等.安徽逍遥钨多金属矿床成矿物质来源与成矿:碳、硫和铅同位素证据[J].中国地质,2013,40(2):566-579.
[27]张德会.流体的沸腾和混合在热液成矿中的意义[J].地球科学进展,1997,12(6):546-552.
[28]卢焕章,单强.金属矿床的成矿流体成分和流体包裹体[J].岩石学报,2015,31(4):1108-1116.
[29]周涛发,范裕,袁峰,等.安徽庐枞盆地泥河铁矿床与膏盐层的成因联系及矿床成矿模式[J].地质学报,2014,88(4):562-573.
[30]左晓敏,杜杨松,曹毅,等.安徽桂花冲铜矿床成矿流体演化特征研究[J].矿床地质,2016,35(1):117-129.
[31]周小栋.宁芜北部脉状铜矿床成因及成矿机制研究[D].合肥:合肥工业大学,2013:1-74.