磁铁石英岩铁运输沉淀的pH值条件约束:以朝鲜半岛龙渊铁矿床为例
|
摘要
前寒武纪时期铁矿形成过程中铁物质如何迁移的研究,已取得了众多科研成果,但仍有些问题未得到很好的解决。尤其是对陆壳来源性铁矿床(非Algoma类型)的成因,仍然具有诸多争议,焦点主要集中在铁迁移问题。笔者以朝鲜半岛龙渊铁矿床为例研究了铁介质形成和运输的问题。首先通过铁矿石的地球化学研究和前人研究结果的考察,发现此铁矿床不属于Algoma类型,而是在强酸性介质条件下陆壳物质风化、移动和沉积而形成的。那么为什么会出现如此强大的酸性环境条件呢?为了揭示这一点,对在当时环境下把水的性质能够变成酸性的物质进行了热力学计算。研究结果表明,当硫化物如黄铁矿风化时,形成了能够使铁源物质风化和迁移的介质。这些结果也符合这样一个事实,即目前从富含硫化物地层淋沥的水的pH值小于3.5,并且铁含量远高于非硫化物类型的地层。本次研究结果表明,陆壳来源的铁矿床形成过程中,不能忽视硫化物的风化作用。
Many accomplishments are made in the mechanistic study of iron source material migration for the formation of large-scale iron ore deposits during the Precambrian period.However,a few factors have yet to be fully resolved.In particular,still in debate are multiple theories on the genesis of cast iron deposits(non-Algoma type)of continental source.We have investigated the continental migration of iron source materials for the Ryongyon iron ore deposits in the Korean Peninsula as an example.From our geochemical study and the work of previous researchers,we showed that the iron ore was not Algoma type but formed from migration and sedimentation of weathered continental source materials under strong acidic conditions.As we know,during the Precambrian time,oxygen was depleted in the atmosphere and water with no ozone layers formed therefore no plants grew on land.Then,how did such a strong acidic environment occur?To clarify,we performed thermodynamic calculations on prevailing materials(at the time)that could convert water into acid in the environment.The results revealed that,when sulphide(such as pyrite)weathering occurred,it developed an iron source capable of medium degree weathering and transport.This result is consistent with the fact that the pH value was less than 3.5 for waters from the sulphide-rich stratum where iron content was much higher than in non-sulphide containing strata.Thus we conclude that sulphide weathering played a non-negligible role in the formation of continental source iron deposits.
Many accomplishments are made in the mechanistic study of iron source material migration for the formation of large-scale iron ore deposits during the Precambrian period.However,a few factors have yet to be fully resolved.In particular,still in debate are multiple theories on the genesis of cast iron deposits(non-Algoma type)of continental source.We have investigated the continental migration of iron source materials for the Ryongyon iron ore deposits in the Korean Peninsula as an example.From our geochemical study and the work of previous researchers,we showed that the iron ore was not Algoma type but formed from migration and sedimentation of weathered continental source materials under strong acidic conditions.As we know,during the Precambrian time,oxygen was depleted in the atmosphere and water with no ozone layers formed therefore no plants grew on land.Then,how did such a strong acidic environment occur?To clarify,we performed thermodynamic calculations on prevailing materials(at the time)that could convert water into acid in the environment.The results revealed that,when sulphide(such as pyrite)weathering occurred,it developed an iron source capable of medium degree weathering and transport.This result is consistent with the fact that the pH value was less than 3.5 for waters from the sulphide-rich stratum where iron content was much higher than in non-sulphide containing strata.Thus we conclude that sulphide weathering played a non-negligible role in the formation of continental source iron deposits.
引文
[1]LASCELLES D F.Black smokers and density currents:a uniformitarian model for the genesis of banded iron-formations[J].Ore Geology Reviews,2007,32(1/2):381-411.
[2]STEINHOEFEL G,BLANCKENBURG F V,HORN I,et al.Deciphering formation processes of banded iron formations from the Transvaal and the Hamersley successions by combined Si and Fe isotope analysis using UV fem to second laser ablation[J].Geochimica et Cosmochimica Acta,2010,74(9):2677-2696.
[3]ROY S,VENKATESH A S.Mineralogy and geochemistry of banded iron formation and iron ores from eastern India with implications on their genesis[J].Journal of Earth System Science,2009,118(6):619-641.
[4]WU H Y,NIU X L,ZHANG L C,et al.Geology and geochemistry of the Macheng Algoma-type banded iron-formation,North China Craton:constraints on mineralization events and genesis of high-grade iron ores[J].Journal of Asian Earth Sciences,2015,113(3):1179-1196.
[5]TRENDALL A.Iron formation:the sedimentary product of a complex interplay among mantle,tectonic,oceanic,and biospheric processes:a discussion[J].Economic Geology,2012,107(2):377-378.
[6]LI H Z,ZHAI M G,ZHANG L C,et al.Mineralogical and microfabric characteristics of magnetite in the Wuyang Precambrian BIFs,southern North China Craton:implications for genesis and depositional processes of the associated BIFs[J].Journal of Asian Earth Sciences,2014,94:267-281.
[7]MOON I K,LEE I S,YANG X Y.Geochemical constraints on the genesis of the Algoma-type banded iron formation(BIF)in Yishui County,western Shandong Province,North China Craton[J].Ore Geology Reviews,2017,89:931-945.
[8]DAI Y P,ZHANG L C,ZHU M T,et al.The composition and genesis of the Mesoarchean Dagushan banded iron formation(BIF)in the Anshan area of the North China Craton[J].Ore Geology Reviews,2014,63:353-373.
[9]ZHU X Q,TANG H S,SUN X H.Genesis of banded iron formations:a series of experimental simulations[J].Ore Geology Reviews,2014,63:465-469.
[10]EGGLSEDER M S,CRUDEN A R,DALSTRA H J,et al.The role of deformation in the formation of banded iron formation hosted high-grade iron ore deposits,Hamersley Province(Australia)[J].Precambrian Research,2017,296:62-77.
[11]ROSIERE C A,CHEMALE F.Genesis of banded iron-formations:a discussion[J].Economic Geology,1996,91(2):466-468.
[12]AYRES D E.Genesis of iron-bearing minerals in banded iron formation mesobands in the Dales Gorge member,Hamersley group,Western Australia[J].Economic Geology,1972,67(8):1214-1233.
[13]CASTRO L O.Genesis of banded iron-formations:reply[J].Economic Geology,1996,91(2):468-469.
[14]RASMUS H,LUKE O,KURT K.Neoarchean banded iron formation within a~2620Ma turbidite-dominated deep-water basin,Slave craton,NW Canada[J].Precambrian Research,2017,292:130-151.
[15]MISHRA M.Geochemistry of Late Archaean shaly BIFformed by oxicexogenic processes:an example from Ramagiri schist belt,Dharwar Craton,India[J].Acta Geochimica,2015,34(3):362-378.
[16]SOS′NICKA M,BAKKER R J,BROMAN C,et al.Fluid types and their genetic meaning for the BIF-hosted iron ores,KrivoyRog,Ukraine[J].Ore Geology Reviews,2015,68:171-194.
[17]兰彩云,张连昌,赵太平.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(7):2567-2582.
[18]张连昌,翟明国,万渝生,等.华北克拉通前寒武纪BIF铁矿研究:进展与问题[J].岩石学报,2012(11):3431-3445.
[19]CANFIELD D E.Reactive iron in marine sediments[J].Geochimica et Cosmochimica Acta,1989,53(3):619-32.
[20]LABERGE G L.Possible biological origin of Precambrian iron formation[J].Economic Geology,1973,68(7):1098-1109.
[21]CASTRO L O.Genesis of banded iron-formations[J].Economic Geology,1994,89(6):1384-1397.
[22]MONICA M,LYDIA L,MARCUS K,et al.Iron isotope and REE+Y composition of the Caue banded iron formation and related iron ores of the Quadrilatero Ferrifero,Brazil[J].Mineralium Deposita,2017,52(2):159-180.
[23]HOLM N G.Biogenic genesis of banded iron formation from hydrothermal solutions[J].Origins of Life and Evolution of the Biosphere,1986,16:3-4.
[24]YANG X Y,LIU L,LEE I S,et al.A review on the Huoqiu banded iron formation(BIF),southeast margin of the North China Craton:genesis of iron deposits and implications for exploration[J].Ore Geology Reviews,2014,63:418-443.
[25]RAVIKUMAR C,BANDYOPADHYAYA R.Mechanistic study on magnetite nanoparticle formation by thermal decomposition and coprecipitation routes[J].The Journal of Physical Chemistry C,2011,115(5):1380-1387.
[26]RASMUSSEN B,MUHLING J R.Making magnetite late again:evidence for widespread magnetite growth by thermal decomposition of siderite in Hamersley banded iron formations[J].Precambrian Research,2018,306:64-93.
[27]ALIAHMAD M,MOGHADDAM N N.Synthesis of maghemite(γ-Fe2O3)nanoparticles by thermal-decomposition of magnetite(Fe3O4)nanoparticles[J].Materials Science-Poland,2013,31(2):264-268.
[28]朝鲜地质图幅52[R].平壤:资源开发部,1988:26-74(朝文).
[29]李竹楠,刘宗乐,白伊成,等.朝鲜地质构成1[M].平壤:工业出版社,1990:231-274(朝文).
[30]PAEK R J,LI J N,KIM Y H,et al.Geology of Korea[M].Pyongyang:Foreign Languages Books Publishing House,1993:31-51.
[31]KASTING J F.Theoretical constraints on oxygen and carbon dioxide concentrations in the Precambrian atmosphere[J].Precambrian Research,1987,34:205-229.
[32]巫锡勇,贺玉龙,魏有仪,等.黑色岩层的风化特征研究[J].地质地球化学,2001,29(2):17-23.
[33]巫锡勇.黑色岩层的风化过程及其热力学分析[M].北京:科学出版社,2008:56-95.
[34]巫锡勇.黑色岩层黏土化过程的硫化矿物氧化动力学机理研究[J].学术动态,2012(1):36-39.
[35]廖昕.黑色页岩化学风化特征及其黄铁矿氧化动力学研究[D].成都:西南交通大学,2013:40-60.
[36]王楠.酸性条件下黄铁矿酸化过程的电化学研究[D].南京:南京理工大学,2012:32-65.
[37]李福春,李莎,杨用钊,等.源生硅酸盐矿物风化产物的研究进展:以云母和长石为例[J].岩石矿物杂志,2006,25(5):440-448.
[38]胡华.黑色泥页岩中黄铁矿与有机质含量的关系及勘探意义[D].荆州:长江大学,2012:46-80.
[39]RIMSTIDT J D,VAUGHAN D J.Pyrite oxidation:a stateof-the-art assessment of the reaction mechanism[J].Geochimica et Cosmochimica Acta,2003,67(5):873-880.
[40]RAISWELL R,CANFIELD D E.Sources of iron for pyrite formation in marine sediments[J].American Journal of Science,1998,298(3):219-245.
[41]CHIGIRA M,SIDLE R C.The effects of environmental changes on weathering,gravitational rock deformation,and landslides,environmental changes and geomorphic hazards in forests[M].New York:CABI Publishing,2002:101-122.
[42]WU Z J,REN D Z,ZHOU H Y,et al.Sulfate reduction and formation of iron sulfide minerals in near shore sediments from Qi'ao Island,Pearl River Estuary,Southern China[J].Quaternary International,2017,452:137-147.
[2]STEINHOEFEL G,BLANCKENBURG F V,HORN I,et al.Deciphering formation processes of banded iron formations from the Transvaal and the Hamersley successions by combined Si and Fe isotope analysis using UV fem to second laser ablation[J].Geochimica et Cosmochimica Acta,2010,74(9):2677-2696.
[3]ROY S,VENKATESH A S.Mineralogy and geochemistry of banded iron formation and iron ores from eastern India with implications on their genesis[J].Journal of Earth System Science,2009,118(6):619-641.
[4]WU H Y,NIU X L,ZHANG L C,et al.Geology and geochemistry of the Macheng Algoma-type banded iron-formation,North China Craton:constraints on mineralization events and genesis of high-grade iron ores[J].Journal of Asian Earth Sciences,2015,113(3):1179-1196.
[5]TRENDALL A.Iron formation:the sedimentary product of a complex interplay among mantle,tectonic,oceanic,and biospheric processes:a discussion[J].Economic Geology,2012,107(2):377-378.
[6]LI H Z,ZHAI M G,ZHANG L C,et al.Mineralogical and microfabric characteristics of magnetite in the Wuyang Precambrian BIFs,southern North China Craton:implications for genesis and depositional processes of the associated BIFs[J].Journal of Asian Earth Sciences,2014,94:267-281.
[7]MOON I K,LEE I S,YANG X Y.Geochemical constraints on the genesis of the Algoma-type banded iron formation(BIF)in Yishui County,western Shandong Province,North China Craton[J].Ore Geology Reviews,2017,89:931-945.
[8]DAI Y P,ZHANG L C,ZHU M T,et al.The composition and genesis of the Mesoarchean Dagushan banded iron formation(BIF)in the Anshan area of the North China Craton[J].Ore Geology Reviews,2014,63:353-373.
[9]ZHU X Q,TANG H S,SUN X H.Genesis of banded iron formations:a series of experimental simulations[J].Ore Geology Reviews,2014,63:465-469.
[10]EGGLSEDER M S,CRUDEN A R,DALSTRA H J,et al.The role of deformation in the formation of banded iron formation hosted high-grade iron ore deposits,Hamersley Province(Australia)[J].Precambrian Research,2017,296:62-77.
[11]ROSIERE C A,CHEMALE F.Genesis of banded iron-formations:a discussion[J].Economic Geology,1996,91(2):466-468.
[12]AYRES D E.Genesis of iron-bearing minerals in banded iron formation mesobands in the Dales Gorge member,Hamersley group,Western Australia[J].Economic Geology,1972,67(8):1214-1233.
[13]CASTRO L O.Genesis of banded iron-formations:reply[J].Economic Geology,1996,91(2):468-469.
[14]RASMUS H,LUKE O,KURT K.Neoarchean banded iron formation within a~2620Ma turbidite-dominated deep-water basin,Slave craton,NW Canada[J].Precambrian Research,2017,292:130-151.
[15]MISHRA M.Geochemistry of Late Archaean shaly BIFformed by oxicexogenic processes:an example from Ramagiri schist belt,Dharwar Craton,India[J].Acta Geochimica,2015,34(3):362-378.
[16]SOS′NICKA M,BAKKER R J,BROMAN C,et al.Fluid types and their genetic meaning for the BIF-hosted iron ores,KrivoyRog,Ukraine[J].Ore Geology Reviews,2015,68:171-194.
[17]兰彩云,张连昌,赵太平.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(7):2567-2582.
[18]张连昌,翟明国,万渝生,等.华北克拉通前寒武纪BIF铁矿研究:进展与问题[J].岩石学报,2012(11):3431-3445.
[19]CANFIELD D E.Reactive iron in marine sediments[J].Geochimica et Cosmochimica Acta,1989,53(3):619-32.
[20]LABERGE G L.Possible biological origin of Precambrian iron formation[J].Economic Geology,1973,68(7):1098-1109.
[21]CASTRO L O.Genesis of banded iron-formations[J].Economic Geology,1994,89(6):1384-1397.
[22]MONICA M,LYDIA L,MARCUS K,et al.Iron isotope and REE+Y composition of the Caue banded iron formation and related iron ores of the Quadrilatero Ferrifero,Brazil[J].Mineralium Deposita,2017,52(2):159-180.
[23]HOLM N G.Biogenic genesis of banded iron formation from hydrothermal solutions[J].Origins of Life and Evolution of the Biosphere,1986,16:3-4.
[24]YANG X Y,LIU L,LEE I S,et al.A review on the Huoqiu banded iron formation(BIF),southeast margin of the North China Craton:genesis of iron deposits and implications for exploration[J].Ore Geology Reviews,2014,63:418-443.
[25]RAVIKUMAR C,BANDYOPADHYAYA R.Mechanistic study on magnetite nanoparticle formation by thermal decomposition and coprecipitation routes[J].The Journal of Physical Chemistry C,2011,115(5):1380-1387.
[26]RASMUSSEN B,MUHLING J R.Making magnetite late again:evidence for widespread magnetite growth by thermal decomposition of siderite in Hamersley banded iron formations[J].Precambrian Research,2018,306:64-93.
[27]ALIAHMAD M,MOGHADDAM N N.Synthesis of maghemite(γ-Fe2O3)nanoparticles by thermal-decomposition of magnetite(Fe3O4)nanoparticles[J].Materials Science-Poland,2013,31(2):264-268.
[28]朝鲜地质图幅52[R].平壤:资源开发部,1988:26-74(朝文).
[29]李竹楠,刘宗乐,白伊成,等.朝鲜地质构成1[M].平壤:工业出版社,1990:231-274(朝文).
[30]PAEK R J,LI J N,KIM Y H,et al.Geology of Korea[M].Pyongyang:Foreign Languages Books Publishing House,1993:31-51.
[31]KASTING J F.Theoretical constraints on oxygen and carbon dioxide concentrations in the Precambrian atmosphere[J].Precambrian Research,1987,34:205-229.
[32]巫锡勇,贺玉龙,魏有仪,等.黑色岩层的风化特征研究[J].地质地球化学,2001,29(2):17-23.
[33]巫锡勇.黑色岩层的风化过程及其热力学分析[M].北京:科学出版社,2008:56-95.
[34]巫锡勇.黑色岩层黏土化过程的硫化矿物氧化动力学机理研究[J].学术动态,2012(1):36-39.
[35]廖昕.黑色页岩化学风化特征及其黄铁矿氧化动力学研究[D].成都:西南交通大学,2013:40-60.
[36]王楠.酸性条件下黄铁矿酸化过程的电化学研究[D].南京:南京理工大学,2012:32-65.
[37]李福春,李莎,杨用钊,等.源生硅酸盐矿物风化产物的研究进展:以云母和长石为例[J].岩石矿物杂志,2006,25(5):440-448.
[38]胡华.黑色泥页岩中黄铁矿与有机质含量的关系及勘探意义[D].荆州:长江大学,2012:46-80.
[39]RIMSTIDT J D,VAUGHAN D J.Pyrite oxidation:a stateof-the-art assessment of the reaction mechanism[J].Geochimica et Cosmochimica Acta,2003,67(5):873-880.
[40]RAISWELL R,CANFIELD D E.Sources of iron for pyrite formation in marine sediments[J].American Journal of Science,1998,298(3):219-245.
[41]CHIGIRA M,SIDLE R C.The effects of environmental changes on weathering,gravitational rock deformation,and landslides,environmental changes and geomorphic hazards in forests[M].New York:CABI Publishing,2002:101-122.
[42]WU Z J,REN D Z,ZHOU H Y,et al.Sulfate reduction and formation of iron sulfide minerals in near shore sediments from Qi'ao Island,Pearl River Estuary,Southern China[J].Quaternary International,2017,452:137-147.