安徽安庆铜铁矿床矽卡岩岩相学和矿物学特征及意义
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摘要
安庆铜铁矿床系长江中下游铁铜成矿带中一典型矽卡岩型矿床。矿体产于月山岩体与下三叠统南陵湖组碳酸盐岩之间的接触带,外接触带矽卡岩中透辉石富集,以铁铜矿化为主;内接触带矽卡岩中石榴子石富集,以铜矿化为主。岩相学研究表明研究区含铜矽卡岩演化经历了矽卡岩期和热液蚀变期,其中,矽卡岩期包括早期矽卡岩阶段、磁铁矿阶段和晚期矽卡岩阶段;热液蚀变期包括早期热液交代阶段、石英-硫化物阶段和石英-碳酸盐阶段。大规模的黄铜矿化发生于石英-硫化物阶段。矿物学研究表明,石榴子石均为钙铁榴石,早期矽卡岩阶段的粒状石榴子石发育韵律环带,其FeO和Al2O3含量表现为振荡变化。与粒状石榴子石相比,晚期矽卡岩阶段脉状石榴子石的And组分更高。早期矽卡岩阶段的粒状辉石为透辉石,具有环带结构,由核部到边部MgO含量减少,FeO含量增加;晚期矽卡岩阶段的脉状辉石为钙铁辉石。空间上,从外接触带到内接触带,辉石的MgO含量与石榴子石的Al2O3含量分别减少,而FeO含量均分别增加。岩相学、矿物学,结合已有地球化学研究成果综合表明,安庆铜铁矿矽卡岩为岩浆热液接触交代成因,Mg来自碳酸盐岩,由外带向内带迁移;Fe来自岩浆热液,由内带向外带迁移,由于磁铁矿阶段的温压条件改变,Fe在外接触带以磁铁矿的形式沉淀富集。
Anqing copper-iron deposit is a typical skarn-type deposit along the middle and lower Yangtze River iron-copper metallogenic belt.The ore bodies located in the contact zone between Yueshan pluton and carbonate rock of Nanlinghu Formation of Lower Triassic.Skarns in exocontact zone are rich in diopside with iron-copper mineralization and skarns in internal contact zone are rich in garnet with copper mineralization.Petrographic studies show that the evolution of the copper silicon skarn in the area experienced skarn period and hydrothermal alteration period.The skarn period includes the early stage of skarn,magnetite stage and late stage of skarn,and the hydrothermal alteration period includes he early hydrothermal stage,quartz-sulfide stage and quartz-carbonate stage.Massive chalcopyrite mineralization mainly occurred in quartz-sulfide stage.Mineralogical studies suggest that the garnets are andradite,granular garnet of the early stage of skarn develops rhythm zoning with oscillation of FeO and Al2O3 content.Compared with granular garnet,the vein-shape garnet of late stage skarn is higher in andradite end-member.The granular pyroxene in the early skarn stage is diopside with ring structure,its MgO content gradually reduced from the core to the edge,while FeO content gradually increased.Vein-shape pyroxene in the late skarn stage is hedenbergite.In spatial,from exocontact zone to internal contact zone,MgO content of pyroxene and Al2O3 content of garnet is reduced,while FeO content of both pyroxene and garnet are increased.Petrography,mineralogy,combined with the existing geochemical research show that skarn of Anqing copper-iron deposit are magmatic-hydrothermal contact metasomatic origin.Mg came from carbonate rocks,migrated from exocontact zone to internal contact zone.Fe came from magmatic hydrothermal,migrated from internal contact zone to exocontact zone.Due to the change of temperature and pressure conditions in magnetite stage,Fe precipitated and enriched in the exocontact zone in the form of magnetite.
Anqing copper-iron deposit is a typical skarn-type deposit along the middle and lower Yangtze River iron-copper metallogenic belt.The ore bodies located in the contact zone between Yueshan pluton and carbonate rock of Nanlinghu Formation of Lower Triassic.Skarns in exocontact zone are rich in diopside with iron-copper mineralization and skarns in internal contact zone are rich in garnet with copper mineralization.Petrographic studies show that the evolution of the copper silicon skarn in the area experienced skarn period and hydrothermal alteration period.The skarn period includes the early stage of skarn,magnetite stage and late stage of skarn,and the hydrothermal alteration period includes he early hydrothermal stage,quartz-sulfide stage and quartz-carbonate stage.Massive chalcopyrite mineralization mainly occurred in quartz-sulfide stage.Mineralogical studies suggest that the garnets are andradite,granular garnet of the early stage of skarn develops rhythm zoning with oscillation of FeO and Al2O3 content.Compared with granular garnet,the vein-shape garnet of late stage skarn is higher in andradite end-member.The granular pyroxene in the early skarn stage is diopside with ring structure,its MgO content gradually reduced from the core to the edge,while FeO content gradually increased.Vein-shape pyroxene in the late skarn stage is hedenbergite.In spatial,from exocontact zone to internal contact zone,MgO content of pyroxene and Al2O3 content of garnet is reduced,while FeO content of both pyroxene and garnet are increased.Petrography,mineralogy,combined with the existing geochemical research show that skarn of Anqing copper-iron deposit are magmatic-hydrothermal contact metasomatic origin.Mg came from carbonate rocks,migrated from exocontact zone to internal contact zone.Fe came from magmatic hydrothermal,migrated from internal contact zone to exocontact zone.Due to the change of temperature and pressure conditions in magnetite stage,Fe precipitated and enriched in the exocontact zone in the form of magnetite.
引文
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[13]陈江峰,李学明,周泰禧,等.安徽月山岩体的40Ar/39Ar年龄及与其有关的成矿时代估计[J].现代地质,1991,5(1):91-99.
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[19]向文帅.安徽省安庆铜铁矿床特征及成因[M].北京:中国地质大学硕士论文,2010.
[20]张智宇,杜杨松,张静,等.安徽贵池铜山矽卡岩型铜矿床蚀变矿化分带特征及其成因[J].矿床地质,2010,29(6):999-1016.
[21]Burton J C,Taylor L A,Chou I M.The fO2-T and fS2-T stability relations of hedenbergite and of hedenbergite-johannsenite solid solu-tions[J].Economic Geology,1982,77:764-783.
[22]赵一鸣,张轶男,林文蔚.我国夕卡岩矿床中的辉石和似辉石特征及其与金属矿化的关系[J].矿床地质,1997,(4):318-329.
[23]梁祥济.钙铝-钙铁系列石榴石的特征及其交代机理[J].岩石矿物学杂志,1994,13(4):342-352.
[24]赵劲松,Newberry R J.对柿竹园夕卡岩成因及其成矿作用的新认识[J].矿物学报,1996,16(4):442-449.
[25]王玉荣,樊文苓,郁云妹.碱交代与铁矿形成的地球化学机理探讨[J].地球化学,1981,(1):95-103.
[26]艾永富,金玲年.石榴石成分与矿化关系的初步研究[J].北京大学学报:自然科学版,1981,1:83-90.
[27]赵斌,李统锦,李昭平,等.我国一些矿区矽卡岩中石榴石的研究[J].矿物学报,1982,(4):296-304.
[28]Berman R G,Brown T H,Greenwood H J.An internally consistent thermodynamic data base for minerals in the system Na2O-K2O-CaO-MgO-FeO-SiO2-Al2O3-Fe2O3-TiO2-H2O-CO2[J].Atomic Energy of Canada Technical Report,1985,TR-337:362.
[29]周涛发,岳书仓.月山地区铜成矿作用的同位素地球化学研究[J].矿床地质,1996,15(4):341-350.
[30]杨光树,温汉捷,胡瑞忠,等.安徽月山岩体岩石地球化学特征及成因[J].矿物学报,2007,27(3/4):406-413.
[31]邪凤鸣.安徽沿江中生代侵入岩的基本特征[J].安徽地质,1991,1(1):28-38.
[2]束学福.安庆夕卡岩型铁铜矿床地质地球化学特征及铁质来源研究[J].矿物岩石地球化学通报,2004,23(3):219-224.
[3]周涛发,岳书仓,柯韵徽.安庆铜矿床成矿流体演化及矿田成岩一成矿模式[J].安徽地质,1998,8(4):4-6.
[4]周涛发,岳书仓.安徽月山矿田铜矿床的形成机制[J].长春地质学院学报,1997,27(3):311-316.
[5]邱瑞龙.安徽月山高钾闪长岩岩石学特征及岩石成因探讨[J].地质论评,1992,38(2):97-108.
[6]张乐骏,周涛发,范裕,等.安徽月山岩体的锆石SHRIMPU-Pb定年及其意义[J].岩石学报,2008,24(08):1725-1732.
[7]刘园园,马昌前,张超,等.安徽月山闪长岩的成因探讨-锆石U-Pb定年及Hf同位素证据[J].地质科技情报,2009,28(5):22-30.
[8]许逢明,杜杨松,王功文,等.安徽月山复式岩体锆石SHRIMPU-Pb年龄和地球化学特征及其地质意义[J].矿物岩石,2012,32(1):61-66.
[9]郭吉保,钱雅倩,黄耀生.安庆矽卡岩矿床的氧同位素交换动力学[J].火山地质与矿产,2000,21(1):23-29.
[10]Pan Y,Dong P.The lower changjiang(Yangzi/Yangtze Riv-er)metallogenic belt,east china,intrusion and wall rockhosted Cu-Fe-Au.Mo.Zn.Pb.Ag deposits[J].Ore Geology Reviews,1999,15:177-242.
[11]周涛发,岳书仓.安徽月山地区成岩成矿作用关系研究[J].火山地质与矿产,1995,16(2):55-66.
[12]董树文,邱瑞龙.安庆月山地区构造作用与岩浆活动[M].北京:地质出版社,1993,15-141.
[13]陈江峰,李学明,周泰禧,等.安徽月山岩体的40Ar/39Ar年龄及与其有关的成矿时代估计[J].现代地质,1991,5(1):91-99.
[14]周涛发,岳书仓.安徽月山地区成岩-成矿关系研究[J].火山地质与矿产,1995,16(2):55-66.
[15]刘亮明,周瑞超,赵崇斌.构造应力环境对浅成岩体成矿系统的制约:从安庆月山岩体冷却过程动力学计算模拟结果分析[J].岩石学报,2010,26(9):2 869-2 878.
[16]Zhou TF,Yuan F,Yue SC.Geochemistry and evolution of ore-forming fluids of the Yueshan Cu-Au skarn and vein-type deposits,AnhuiProvinces,South China[J].Ore Geology Reviews,2007,31:279-303.
[17]袁见齐,朱上庆,翟裕生,等.矿床学[M].北京:地质出版社,1985,1-346.
[18]袁峰,周涛发,刘晓东,等.安徽安庆铜矿床稀土元素地球化学研究[J].中国稀土学报,2002,20(3):199-202.
[19]向文帅.安徽省安庆铜铁矿床特征及成因[M].北京:中国地质大学硕士论文,2010.
[20]张智宇,杜杨松,张静,等.安徽贵池铜山矽卡岩型铜矿床蚀变矿化分带特征及其成因[J].矿床地质,2010,29(6):999-1016.
[21]Burton J C,Taylor L A,Chou I M.The fO2-T and fS2-T stability relations of hedenbergite and of hedenbergite-johannsenite solid solu-tions[J].Economic Geology,1982,77:764-783.
[22]赵一鸣,张轶男,林文蔚.我国夕卡岩矿床中的辉石和似辉石特征及其与金属矿化的关系[J].矿床地质,1997,(4):318-329.
[23]梁祥济.钙铝-钙铁系列石榴石的特征及其交代机理[J].岩石矿物学杂志,1994,13(4):342-352.
[24]赵劲松,Newberry R J.对柿竹园夕卡岩成因及其成矿作用的新认识[J].矿物学报,1996,16(4):442-449.
[25]王玉荣,樊文苓,郁云妹.碱交代与铁矿形成的地球化学机理探讨[J].地球化学,1981,(1):95-103.
[26]艾永富,金玲年.石榴石成分与矿化关系的初步研究[J].北京大学学报:自然科学版,1981,1:83-90.
[27]赵斌,李统锦,李昭平,等.我国一些矿区矽卡岩中石榴石的研究[J].矿物学报,1982,(4):296-304.
[28]Berman R G,Brown T H,Greenwood H J.An internally consistent thermodynamic data base for minerals in the system Na2O-K2O-CaO-MgO-FeO-SiO2-Al2O3-Fe2O3-TiO2-H2O-CO2[J].Atomic Energy of Canada Technical Report,1985,TR-337:362.
[29]周涛发,岳书仓.月山地区铜成矿作用的同位素地球化学研究[J].矿床地质,1996,15(4):341-350.
[30]杨光树,温汉捷,胡瑞忠,等.安徽月山岩体岩石地球化学特征及成因[J].矿物学报,2007,27(3/4):406-413.
[31]邪凤鸣.安徽沿江中生代侵入岩的基本特征[J].安徽地质,1991,1(1):28-38.
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