辽宁本溪大台沟铁矿床地球化学特征及成因探讨
|
摘要
为探讨辽宁大台沟铁矿床的成矿物质来源及形成环境,选取典型铁矿石5块进行主量元素、微量元素和稀土元素分析测试。结果显示:大台沟铁矿床保存有明显的化学沉积特征,化学成分主要由Fe_2O_3,FeO和SiO_2组成(Fe_2O_3+FeO+SiO_2=87.33%～96%),其他组分(MnO,MgO,CaO,Na_2O,K_2O,TiO_2,P_2O_5,Al_2O_3)含量较低;页岩标准化后的稀土元素配分曲线显示为稀土总量低(ΣREE平均为19.65×10~(-6)),轻稀土元素相对亏损,重稀土元素相对富集;且具有一定的Eu(Eu/Eu~*=1.52～2.72),Y(Y/Y~*=1.18～1.52),La(La/La~*=1.17～2.26)的正异常,弱的Ce(Ce/Ce~*=0.79～0.92)异常;Y/Ho值平均34.19接近于海水的分布范围;Sr/Ba值平均1.79,属于火山岩和海相沉积物;Ti/V值平均38.84,属于火山建造。这些特征表明:该矿床的形成可能与海相火山沉积物有关,属于火山沉积变质型铁矿范围;成矿物质来源于热水和海水的混合作用;矿床形成于相对于缺氧的环境。
Major and trace elements of five typical iron ores and host rocks from banded iron formation(BIF) in the Benxi area of Liaoning Province are analyzed in order to study the origin of ore-forming material and metallogenic environment.The results show that the BIF has obvious chemical deposition characteristics.The average bulk compositions of ores are characterized by enrichment of Fe_2O_3,FeO and SiO_2(Fe_2O_3+FeO+SiO_2=87.33%～96%),while MnO,MgO,CaO,Na_2O,K_2O,TiO_2,P_2O_5,Al_2O_3 have low contents.In addition,the shale-normalized REE distribution patterns of the ores display very low(ΣREE=19.65×10~(-6)) REE concentrations,depletion of LREE and enrichment of HREE.The patterns also show positive anomalies of Eu(Eu/Eu~*=1.52～2.72),Y(Y/Y~*=1.18～1.52) and La(La/La~*=1.17～2.26) and weak Ce(Ce/Ce~*=0.79～0.92) anomalies.Moreover,the average Y/Ho ratio of ores is 34.19,close to the range of seawater,the average ratio of Sr/Ba is 1.79,characteristic of volcanic and marine sediments and the average ration of Ti/V is 38.84,belonging to volcanic formation.These chemical features indicate that the formation of the BIF is related to marine volcanic sediments and belongs to volcanic sedimentary metamorphic iron deposit,formed in the hypoxic environment with the ore-forming material originated from the mixing of thermal fluid and seawater.
Major and trace elements of five typical iron ores and host rocks from banded iron formation(BIF) in the Benxi area of Liaoning Province are analyzed in order to study the origin of ore-forming material and metallogenic environment.The results show that the BIF has obvious chemical deposition characteristics.The average bulk compositions of ores are characterized by enrichment of Fe_2O_3,FeO and SiO_2(Fe_2O_3+FeO+SiO_2=87.33%～96%),while MnO,MgO,CaO,Na_2O,K_2O,TiO_2,P_2O_5,Al_2O_3 have low contents.In addition,the shale-normalized REE distribution patterns of the ores display very low(ΣREE=19.65×10~(-6)) REE concentrations,depletion of LREE and enrichment of HREE.The patterns also show positive anomalies of Eu(Eu/Eu~*=1.52～2.72),Y(Y/Y~*=1.18～1.52) and La(La/La~*=1.17～2.26) and weak Ce(Ce/Ce~*=0.79～0.92) anomalies.Moreover,the average Y/Ho ratio of ores is 34.19,close to the range of seawater,the average ratio of Sr/Ba is 1.79,characteristic of volcanic and marine sediments and the average ration of Ti/V is 38.84,belonging to volcanic formation.These chemical features indicate that the formation of the BIF is related to marine volcanic sediments and belongs to volcanic sedimentary metamorphic iron deposit,formed in the hypoxic environment with the ore-forming material originated from the mixing of thermal fluid and seawater.
引文
[1] 张东阳,苏慧敏,田磊,等.河南窑场铁矿床成因矿物学研究及其地质意义[J].矿物岩石,2010,30(01):53-63.
[2] 周世泰.鞍山-本溪地区条带状铁矿地质[M].北京:地质出版社,1994.
[3] 沈保丰.华北陆台太古宙绿岩带地质及成矿[M].北京:地质出版社,1994.
[4] 陈光远,黎美华,汪雪芳,等.弓长岭铁矿成因矿物学专辑,第十章,矿床成因[J].矿物岩石,1984,4(02):212-234.
[5] 洪秀伟,庞宏伟,刘学文,等.辽宁本溪大台沟铁矿地质特征[J].中国地质,2010,37(05):1 426-1 433.
[6] 王志宏,郑娇.大台沟铁矿的成因及找矿标志[J].辽宁科技大学学报,2010,33(04):353-355.
[7] 张璟,邵军,鲍庆中,等.辽宁本溪大台沟铁矿地质特征及找矿标志[J].地质与资源,2014,23(04):343-351+356.
[8] 张朋.辽宁本溪大台沟铁矿地球化学特征及其地质意义[J].地质与资源,2016,25(01):56-59.
[9] 沈其韩.华北地台早前寒武纪条带状铁英岩地质特征和形成的地质背景[A].主编:程裕淇.华北地台早前寒武纪地质研究论文集[C].北京:地质出版社,1998,1-30.
[10] 李延河,侯可军,万德芳,等.前寒武纪条带状硅铁建造的形成机制与地球早期的大气和海洋[J].地质学报,2010,84(09):1 359-1 373.
[11] Bau M,Dulski P.Distribution of yttrium and rare-earth elements in the Penge and Kuruman iron-formations,Transvaal Supergroup,South Africa[J].Precambrian Research,1996,79(1-2):37-55.
[12] Sun S S,Mcdonough W F.Chemical and isotopic systematics of oceanic basalts:implications for mantle composition and processes[J].Geological Society London Special Publications,1989,42(1):313-345.
[13] Mclennan S M.Rare earth elements in sedimentary rocks:Influence of provenance and sedimentary processes[J].Reviews in Mineralogy,1989,21(8):169-200.
[14] Spier C A,Oliveira S M B D,Sial A N, et al.Geochemistry and genesis of the banded iron formations of the Cauê Formation,Quadrilátero Ferrífero,Minas Gerais,Brazil[J].Precambrian Research,2007,152(3):170-206.
[15] 兰彩云,张连昌,赵太平,等.河南舞阳铁山庙式BIF铁矿的矿物学与地球化学特征及对矿床成因的指示[J].岩石学报,2013,29(07):2567-2582.
[16] 沈其韩,宋会侠,赵子然.山东韩旺新太古代条带状铁矿的稀土和微量元素特征[J].地球学报,2009,30(06):693-699.
[17] 李树勋,马志红.五台山区变质沉积铁矿地质[M].吉林科学技术出版社,1986.
[18] 翟明国,Windley,B.F.Sills,等.鞍本太古代条带状铁建造(BIF)的稀土及微量元素特征[J].地球化学,1989(03):241-250.
[19] 沈其韩,宋会侠,杨崇辉,等.山西五台山和冀东迁安地区条带状铁矿的岩石化学特征及其地质意义[J].岩石矿物学杂志,2011,30(02):161-171.
[20] Danielson A,M?ller P,Dulski P.The europium anomalies in banded iron formations and the thermal history of the oceanic crust[J].Chemical Geology,1992,97(1-2):89-100.
[21] Bau M.Yttrium and Holmium in South Pacific Seawater:Vertical Distribution and Possible Fractionation Mechanisms[J].Chem Erde,1995,55(1):1-15.
[22] Dymek R F,Klein C.Chemistry,petrology and origin of banded iron-formation lithologies from the 3800 MA isua supracrustal belt,West Greenland[J].Precambrian Research,1988,39(4):247-302.
[23] Danielson A,M?ller P,Dulski P.The europium anomalies in banded iron formations and the thermal history of the oceanic crust[J].Chemical Geology,1992,97(1-2):89-100.
[24] Huston D L,Logan G A.Barite,BIFs and bugs:evidence for the evolution of the Earth′s early hydrosphere[J].Earth & Planetary Science Letters,2004,220(1-2):41-55.
[25] Alexander B W,Bau M,Andersson P, et al.Continentally-derived solutes in shallow Archean seawater:Rare earth element and Nd isotope evidence in iron formation from the 2.9 Ga Pongola Supergroup,South Africa[J].Geochimica Et Cosmochimica Acta,2008,72(2):378-394.
[26] Nozaki Y,Zhang J,Amakawa H.The fractionation between Y and Ho in the marine environment[J].Earth Planet.sci.lett,1997,148(1):329-340.
[27] Byrne R H,Sholkovitz E R.Chapter 158 Marine chemistry and geochemistry of the lanthanides[M]// Handbook on the Physics and Chemistry of Rare Earths.1996:497-593.
[28] Cloud P.Paleoecological significance of the banded iron-formations[J].Economic Geology,1973,68(7):1 135-1 143.
[2] 周世泰.鞍山-本溪地区条带状铁矿地质[M].北京:地质出版社,1994.
[3] 沈保丰.华北陆台太古宙绿岩带地质及成矿[M].北京:地质出版社,1994.
[4] 陈光远,黎美华,汪雪芳,等.弓长岭铁矿成因矿物学专辑,第十章,矿床成因[J].矿物岩石,1984,4(02):212-234.
[5] 洪秀伟,庞宏伟,刘学文,等.辽宁本溪大台沟铁矿地质特征[J].中国地质,2010,37(05):1 426-1 433.
[6] 王志宏,郑娇.大台沟铁矿的成因及找矿标志[J].辽宁科技大学学报,2010,33(04):353-355.
[7] 张璟,邵军,鲍庆中,等.辽宁本溪大台沟铁矿地质特征及找矿标志[J].地质与资源,2014,23(04):343-351+356.
[8] 张朋.辽宁本溪大台沟铁矿地球化学特征及其地质意义[J].地质与资源,2016,25(01):56-59.
[9] 沈其韩.华北地台早前寒武纪条带状铁英岩地质特征和形成的地质背景[A].主编:程裕淇.华北地台早前寒武纪地质研究论文集[C].北京:地质出版社,1998,1-30.
[10] 李延河,侯可军,万德芳,等.前寒武纪条带状硅铁建造的形成机制与地球早期的大气和海洋[J].地质学报,2010,84(09):1 359-1 373.
[11] Bau M,Dulski P.Distribution of yttrium and rare-earth elements in the Penge and Kuruman iron-formations,Transvaal Supergroup,South Africa[J].Precambrian Research,1996,79(1-2):37-55.
[12] Sun S S,Mcdonough W F.Chemical and isotopic systematics of oceanic basalts:implications for mantle composition and processes[J].Geological Society London Special Publications,1989,42(1):313-345.
[13] Mclennan S M.Rare earth elements in sedimentary rocks:Influence of provenance and sedimentary processes[J].Reviews in Mineralogy,1989,21(8):169-200.
[14] Spier C A,Oliveira S M B D,Sial A N, et al.Geochemistry and genesis of the banded iron formations of the Cauê Formation,Quadrilátero Ferrífero,Minas Gerais,Brazil[J].Precambrian Research,2007,152(3):170-206.
[15] 兰彩云,张连昌,赵太平,等.河南舞阳铁山庙式BIF铁矿的矿物学与地球化学特征及对矿床成因的指示[J].岩石学报,2013,29(07):2567-2582.
[16] 沈其韩,宋会侠,赵子然.山东韩旺新太古代条带状铁矿的稀土和微量元素特征[J].地球学报,2009,30(06):693-699.
[17] 李树勋,马志红.五台山区变质沉积铁矿地质[M].吉林科学技术出版社,1986.
[18] 翟明国,Windley,B.F.Sills,等.鞍本太古代条带状铁建造(BIF)的稀土及微量元素特征[J].地球化学,1989(03):241-250.
[19] 沈其韩,宋会侠,杨崇辉,等.山西五台山和冀东迁安地区条带状铁矿的岩石化学特征及其地质意义[J].岩石矿物学杂志,2011,30(02):161-171.
[20] Danielson A,M?ller P,Dulski P.The europium anomalies in banded iron formations and the thermal history of the oceanic crust[J].Chemical Geology,1992,97(1-2):89-100.
[21] Bau M.Yttrium and Holmium in South Pacific Seawater:Vertical Distribution and Possible Fractionation Mechanisms[J].Chem Erde,1995,55(1):1-15.
[22] Dymek R F,Klein C.Chemistry,petrology and origin of banded iron-formation lithologies from the 3800 MA isua supracrustal belt,West Greenland[J].Precambrian Research,1988,39(4):247-302.
[23] Danielson A,M?ller P,Dulski P.The europium anomalies in banded iron formations and the thermal history of the oceanic crust[J].Chemical Geology,1992,97(1-2):89-100.
[24] Huston D L,Logan G A.Barite,BIFs and bugs:evidence for the evolution of the Earth′s early hydrosphere[J].Earth & Planetary Science Letters,2004,220(1-2):41-55.
[25] Alexander B W,Bau M,Andersson P, et al.Continentally-derived solutes in shallow Archean seawater:Rare earth element and Nd isotope evidence in iron formation from the 2.9 Ga Pongola Supergroup,South Africa[J].Geochimica Et Cosmochimica Acta,2008,72(2):378-394.
[26] Nozaki Y,Zhang J,Amakawa H.The fractionation between Y and Ho in the marine environment[J].Earth Planet.sci.lett,1997,148(1):329-340.
[27] Byrne R H,Sholkovitz E R.Chapter 158 Marine chemistry and geochemistry of the lanthanides[M]// Handbook on the Physics and Chemistry of Rare Earths.1996:497-593.
[28] Cloud P.Paleoecological significance of the banded iron-formations[J].Economic Geology,1973,68(7):1 135-1 143.