安徽省霍邱铁矿含铁岩系中斜长片麻岩黑云母-石榴石地球化学特征及其地质指示意义
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摘要
霍邱铁矿是华东地区发现的超大型变质铁矿床。通过对铁矿体的含铁岩系中黑云斜长片麻岩样品电子探针微区分析,从黑云母-石榴石的化学成分分析入手,研究矿物特征和地球化学特征,揭示变质程度与变质作用和成矿条件关系。黑云斜长片麻岩的MF比值为0.39~0.52,均值0.46,A1/Si比值0.23~0.31,具富铁、富硅的特征,原岩恢复为巨厚层状泥质类岩石;黑云斜长片麻岩中黑云母FM=2.25~3.09,均值为2.58,黑云母类别为镁质黑云母。石榴石中w(FeO)28.77%~30.85%,w(MgO)3.54%~5.99%,石榴石中铁铝榴石含量最高,为61.76%~67.40%,以铁铝质系列为主。伴随温度的升高,镁的分配系数黑云母比石榴石高,即KD~(Mg)(均值)=0.57>0.23,温度的升高,铁在黑云母中富集,KDMg的值随温度升高而降低。石榴石-黑云母对变质温度在620℃~650℃之间,变质压力可达0.2GPa~0.8GPa,与乌沙柯娃根据KDFe值估算的温压条件接近;变质程度可达角闪岩相变质。运用热力学Gibbs自由能原理,计算出变质峰期时氧逸度值lnf_(O2)=-11.324~-11.779,氧逸度缓冲剂类型为MH型。综合分析,初步认为本区黑云斜长片麻岩的原岩恢复为巨厚层状富铁的泥质岩类夹部分火山岩;原岩变质时的理化条件是中压,中高温环境,变质峰期氧逸度较高,原岩经历了角闪岩相变质。变质作用的发生使得变质原岩中的铁重新活化并迁移,在高氧逸度条件下,铁被淋滤出来,最终铁硅质岩更加富集成矿。
The geochemical and mineralogical characteristics of biotite and garnet in the biotite plagiogneiss from large scale metamorphic iron ore deposit in Huoqiu area are analyzed by electron microprobe,so as to unravel the relation between metamorphic degree and mineralization conditions.It shows that the MF ratio of the biotite plagiogneiss is 0.39~0.52(average 0.46),with the A1/Si ratio ranging from 0.23 to 0.31,characteristic of enrichment of iron and silicon,and the original rock is mainly huge thick layer of argillaceous rocks.The FM of biotite is 2.25~3.09 in biotite plagioclase with an average of 2.58,belonging to magnesium rich type biotite.The content of w(FeO)in garnet is from 28.77%to 30.85%,the content of w(MgO)is from 3.54%to 5.99%.Almandine makes up 61.76% to 67.40% and belongs to the Ferric aluminum series.With the increase of temperature,the distribution coefficient of magnesium is much higher in biotite than in garnet(0.57>0.23),and with the increase of temperature,magnesium is enriched in biotite than in garnet,and the value of KDMgis decreased with increase of temperature.The metamorphic temperature determined by mineral pair of garnet and biotite is 620 ℃ ~650 ℃ with a metamorphic pressure of 0.2 GPa~0.8 GPa,consistent with Vusakwa in terms of KDFe,characteristic of amphibolite facies.Gibbs free energy calculation of thermodynamics shows that the content of oxygen fugacity from the metamorphism peak is lnf_(O2)=-11.324~-11.779,and the oxygen fugacity buffer type is MH.It is considered that the original rock of plagiogneiss is thick bedded argillaceous rocks intercalated with minor volcanic rocks.The original rocks were metamorphosed under amphibolite facies metamorphism at medium pressure,middle and high temperature during the period of metamorphism,with high oxygen fugacity at the metamorphic peak.Iron in the original rock reactivated and migrated during metamorphism,it was leached out under the condition of high oxygen fugacity,and formed Ferro rich siliceous rock.
The geochemical and mineralogical characteristics of biotite and garnet in the biotite plagiogneiss from large scale metamorphic iron ore deposit in Huoqiu area are analyzed by electron microprobe,so as to unravel the relation between metamorphic degree and mineralization conditions.It shows that the MF ratio of the biotite plagiogneiss is 0.39~0.52(average 0.46),with the A1/Si ratio ranging from 0.23 to 0.31,characteristic of enrichment of iron and silicon,and the original rock is mainly huge thick layer of argillaceous rocks.The FM of biotite is 2.25~3.09 in biotite plagioclase with an average of 2.58,belonging to magnesium rich type biotite.The content of w(FeO)in garnet is from 28.77%to 30.85%,the content of w(MgO)is from 3.54%to 5.99%.Almandine makes up 61.76% to 67.40% and belongs to the Ferric aluminum series.With the increase of temperature,the distribution coefficient of magnesium is much higher in biotite than in garnet(0.57>0.23),and with the increase of temperature,magnesium is enriched in biotite than in garnet,and the value of KDMgis decreased with increase of temperature.The metamorphic temperature determined by mineral pair of garnet and biotite is 620 ℃ ~650 ℃ with a metamorphic pressure of 0.2 GPa~0.8 GPa,consistent with Vusakwa in terms of KDFe,characteristic of amphibolite facies.Gibbs free energy calculation of thermodynamics shows that the content of oxygen fugacity from the metamorphism peak is lnf_(O2)=-11.324~-11.779,and the oxygen fugacity buffer type is MH.It is considered that the original rock of plagiogneiss is thick bedded argillaceous rocks intercalated with minor volcanic rocks.The original rocks were metamorphosed under amphibolite facies metamorphism at medium pressure,middle and high temperature during the period of metamorphism,with high oxygen fugacity at the metamorphic peak.Iron in the original rock reactivated and migrated during metamorphism,it was leached out under the condition of high oxygen fugacity,and formed Ferro rich siliceous rock.
引文
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[6]陆三明,楼金伟,李茂章,等.安徽省霍邱铁矿区及外围铁矿成矿规律及潜力研究[J].安徽地质,2014,24(02):94-98.
[7]蔡志勇,陆三明,王启才,等.安徽省霍邱铁矿成矿特征及构造控矿的深部找矿意义[J].安徽地质,2012,22(04):248-250+255.
[8]王宝富.浅谈安徽霍邱张庄铁矿床围岩特征及成矿作用[J].科技创新导报,2011,(28):56.
[9]杨晓勇,杜贞保,王启才,等.论华北克拉通南缘霍邱群变质作用、形成时代及霍邱BIF铁矿成矿机制[J].岩石学报,2012,28(11):3 476-3 496.
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[12]高执棣.化学热力学基础[D]北京大学出版社,2006.5.
[13]Simonen A.Stratigraphy and Sedimentation of the Svecofenmided Early Archean Super-crustal Rocks in South-Western Finland.Balt Comm Geol,Finland,1953,(160):64-89.
[14]孙世华,于洁.Mg-Fe云母化学成分的解释和分类(Ⅱ)—Mg-Fe云母的自然分类[J].地质科学,1989,(02):176-189.
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[16]Stone D.Temperature and pressure variations in suites of Archean felsic plutonic rocks,Berens river area,northwest superior Province,Ontario,Canada.The Canadian Mineralogist,2000,38(2):455-470.
[17]Henry D J,Guidotti C V,Thomoson J A.The Tisaturation surface for low to medium pressure metapelitic biotites:Implication for geothermonmetry and Ti-substitution mechanisms[J].Am Mineral,2005,90:316-328.
[18]Perchuk L.L.The effect of temperature and pressrure on the equilibrium of natural ironmegnesium mineral.Internet[J].Gdology Rev,1969,11:875-901.
[19]李树勋,刘喜山.石榴石-黑云母共生矿物对地质温度计应用中的问题[J].矿物岩石,1988.6,8(02):248-250+255.
[20]贺高品.区域变质相的划分及其标志[J].中国区域地质,1985,14:80-93.
[21]郭敬辉,翟明国,李永刚,等.华北太古宙高压基性麻粒岩的两类PT轨迹及其构造意义:矿物化学和变质作用研究[J].岩石学报,1998(04):25-30+33-43.
[22]刘平华,刘福来,王舫,等.胶北地体多期变质事件的P-T-t轨迹及其对胶-辽-吉带形成与演化的制约[J].岩石学报,2015,31(10):2 889-2 941.
[23]刘福来.晋蒙交界孔兹岩系熔体参与变质反应的结构特征及其动力学意义[J].岩石学报,1998(02):2-12.
[24]赵博,张德会,石成龙,等.对与氧逸度有关的花岗岩类成矿专属性-含矿性问题的再思考[J].岩石矿物学杂志,2014,33(05):955-964.
[25]Helgeson H C.Theoretical predicition of thermodynamic behaviour of aqueous electrolytes at high pressures and temperatures.IV,Calculation of activity coefficients,osmotic coefficients,and apparent motal and standard and relative partial motal properties to 600℃and 5kbar.Am.J.Sci.1981,281:1 249-1 516.
[26]苏尚国,赖兴运.高压变质作用压力估算的热力学方法[J].地质科技情报,1994(02):91-97.
[27]汪志诚.热力学.统计物理学[D].高等教育出版社,2006.
[28]赖绍聪,周天祯.岩浆氧逸度及其研究进展[J].青海地质,1993(02):64-69.
[29]高学泉.滇西北衙金矿床富碱斑岩岩浆氧逸度对成矿的制约[D].中国地质大学(北京),2017.
[30]韩吟文.地球化学[D].地质出版社,2008.
[31]岳元珍.霍邱群的矿物特征及其变质作用[J].中国地质科学院南京地质矿产研究所所刊,1982(03):1-29.
[32]王西荣,潘家永,李绍侠.汪家冲—郎岭湾地区火山岩型金矿地质特征及成矿模式[J].金属矿山,2016(05):118-124.
[33]赵珊茸,边秋娟,王勤燕.结晶学与矿物学[D].高等教育出版社,2003.10
[34]王贵玲,张薇,梁继运,等.中国地热资源潜力评价[J].地球学报,2017,38(04):449-450+134+451-459.
(1)马连民,李茂章,宋明义,等.1∶5×104安徽省三河尖-润河集幅、桥沟-高塘集幅、蒋集-刘集幅区域地质调查报告[R].安徽省地质矿勘查局:1986.7.7.
(2)李茂章,王西荣.安徽省国土资源厅项目《安徽省霍邱铁矿外围航磁异常查证设计》项目编号:2006-39,2006.
(3)安徽省地质矿产勘查局.中华人民共和国区域地质调查报告:1∶5×104三河尖-运河集、桥沟-高塘集、蒋集-刘集三幅图联测,1986.
(4)安徽省地质矿产勘查局.安徽霍邱铁矿报告.1991.
(5)郭峰.岩浆氧逸度估算及其在斑岩矿床中的应用[PPT].网络课件资料,2017,05.
[2]孙玉宝.安徽霍邱李老庄铁矿-菱镁矿矿床地质特征及矿床成因类型[J].矿产与地质,2007,(05):532-537.
[3]黄华.华北克拉通南缘霍邱BIF铁矿成矿时代、形成环境及成因[D].成都理工大学,2014.
[4]黄华,张连昌,刘显凡,等.霍邱矿田李老庄铁矿地质与地球化学特征及对沉积环境的指示[J].岩石学报,2013,29(07):2 593-2 605.
[5]潘仙敏,杨强,罗通.安徽西部霍邱周油坊铁矿床地球化学特征及成因[J].华东地质,2016,37(01):52-60.
[6]陆三明,楼金伟,李茂章,等.安徽省霍邱铁矿区及外围铁矿成矿规律及潜力研究[J].安徽地质,2014,24(02):94-98.
[7]蔡志勇,陆三明,王启才,等.安徽省霍邱铁矿成矿特征及构造控矿的深部找矿意义[J].安徽地质,2012,22(04):248-250+255.
[8]王宝富.浅谈安徽霍邱张庄铁矿床围岩特征及成矿作用[J].科技创新导报,2011,(28):56.
[9]杨晓勇,杜贞保,王启才,等.论华北克拉通南缘霍邱群变质作用、形成时代及霍邱BIF铁矿成矿机制[J].岩石学报,2012,28(11):3 476-3 496.
[10]周世泰.对17种恢复变质岩原岩的岩石化学方法的检验结果[J].地质论评,1984,(01):81-84.
[11]汪存信,宋昭华.物理化学[D].武汉大学出版社,2003.7.
[12]高执棣.化学热力学基础[D]北京大学出版社,2006.5.
[13]Simonen A.Stratigraphy and Sedimentation of the Svecofenmided Early Archean Super-crustal Rocks in South-Western Finland.Balt Comm Geol,Finland,1953,(160):64-89.
[14]孙世华,于洁.Mg-Fe云母化学成分的解释和分类(Ⅱ)—Mg-Fe云母的自然分类[J].地质科学,1989,(02):176-189.
[15]Foster M D.Interpretation of the composition of trioctahedral micas.US Geological Surevey Scientific Investigations,1960,354:11-49.
[16]Stone D.Temperature and pressure variations in suites of Archean felsic plutonic rocks,Berens river area,northwest superior Province,Ontario,Canada.The Canadian Mineralogist,2000,38(2):455-470.
[17]Henry D J,Guidotti C V,Thomoson J A.The Tisaturation surface for low to medium pressure metapelitic biotites:Implication for geothermonmetry and Ti-substitution mechanisms[J].Am Mineral,2005,90:316-328.
[18]Perchuk L.L.The effect of temperature and pressrure on the equilibrium of natural ironmegnesium mineral.Internet[J].Gdology Rev,1969,11:875-901.
[19]李树勋,刘喜山.石榴石-黑云母共生矿物对地质温度计应用中的问题[J].矿物岩石,1988.6,8(02):248-250+255.
[20]贺高品.区域变质相的划分及其标志[J].中国区域地质,1985,14:80-93.
[21]郭敬辉,翟明国,李永刚,等.华北太古宙高压基性麻粒岩的两类PT轨迹及其构造意义:矿物化学和变质作用研究[J].岩石学报,1998(04):25-30+33-43.
[22]刘平华,刘福来,王舫,等.胶北地体多期变质事件的P-T-t轨迹及其对胶-辽-吉带形成与演化的制约[J].岩石学报,2015,31(10):2 889-2 941.
[23]刘福来.晋蒙交界孔兹岩系熔体参与变质反应的结构特征及其动力学意义[J].岩石学报,1998(02):2-12.
[24]赵博,张德会,石成龙,等.对与氧逸度有关的花岗岩类成矿专属性-含矿性问题的再思考[J].岩石矿物学杂志,2014,33(05):955-964.
[25]Helgeson H C.Theoretical predicition of thermodynamic behaviour of aqueous electrolytes at high pressures and temperatures.IV,Calculation of activity coefficients,osmotic coefficients,and apparent motal and standard and relative partial motal properties to 600℃and 5kbar.Am.J.Sci.1981,281:1 249-1 516.
[26]苏尚国,赖兴运.高压变质作用压力估算的热力学方法[J].地质科技情报,1994(02):91-97.
[27]汪志诚.热力学.统计物理学[D].高等教育出版社,2006.
[28]赖绍聪,周天祯.岩浆氧逸度及其研究进展[J].青海地质,1993(02):64-69.
[29]高学泉.滇西北衙金矿床富碱斑岩岩浆氧逸度对成矿的制约[D].中国地质大学(北京),2017.
[30]韩吟文.地球化学[D].地质出版社,2008.
[31]岳元珍.霍邱群的矿物特征及其变质作用[J].中国地质科学院南京地质矿产研究所所刊,1982(03):1-29.
[32]王西荣,潘家永,李绍侠.汪家冲—郎岭湾地区火山岩型金矿地质特征及成矿模式[J].金属矿山,2016(05):118-124.
[33]赵珊茸,边秋娟,王勤燕.结晶学与矿物学[D].高等教育出版社,2003.10
[34]王贵玲,张薇,梁继运,等.中国地热资源潜力评价[J].地球学报,2017,38(04):449-450+134+451-459.
(1)马连民,李茂章,宋明义,等.1∶5×104安徽省三河尖-润河集幅、桥沟-高塘集幅、蒋集-刘集幅区域地质调查报告[R].安徽省地质矿勘查局:1986.7.7.
(2)李茂章,王西荣.安徽省国土资源厅项目《安徽省霍邱铁矿外围航磁异常查证设计》项目编号:2006-39,2006.
(3)安徽省地质矿产勘查局.中华人民共和国区域地质调查报告:1∶5×104三河尖-运河集、桥沟-高塘集、蒋集-刘集三幅图联测,1986.
(4)安徽省地质矿产勘查局.安徽霍邱铁矿报告.1991.
(5)郭峰.岩浆氧逸度估算及其在斑岩矿床中的应用[PPT].网络课件资料,2017,05.