The metallogenic environment of the Dounan manganese deposit,Southeast Yunnan, China: evidence from geochemistry and M?ssbauer spectroscopic
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摘要
The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, and precipitation of Mn. To better understand its metallogenetic environment, a detailed study was undertaken involving field observation, mineralogical and geochemical and M?ssbauer spectroscopic analyses. The major findings are as follows:(1) Lithofacies paleogeography, sedimentary structural characteristics, and geochemical indexes indicate that the deposits were formed in an epicontinental marine sedimentary basin environment of normal salinity;(2) there were three ore phases including Mn oxides, Mn carbonates, and mixed Mn ores. The ore minerals found were braunite, manganite, Ca-rhodochrosite, manganocalcite, and kutnahorite. Petrographic and mineralogical information indicates that the metallogenic environment was a weakly alkaline and weakly oxidized to weakly reduced environment, and the mineralization occurred near the redox interface;(3) the V/(V + Ni)ratios, δCe and Fe~(2+)/Fe~(3+) found in profiles of Baigu and Gake ore sections show that the redox conditions of the ore-forming environment were continuously changing; and(4) three Fe species, α-Fe_2O_3, para-Fe~(3+), and para-Fe~(2+),were found in hematite and clay mineral samples using M?ssbauer spectrum analysis. The presence and distribution of these Fe species indicate that the deposit was formed in a typical sedimentary environment during the mineralization process. In summary, our study showed that redox was a key factor controlling the mineralization of the Dounan manganese deposit. Our results have led us to the conclusion that transgression and regression caused fluctuations in sea level, which in turn caused the change of the redox environment. M?ssbauer spectroscopy is an effective tool for studying the redox conditions of the paleoenvironment in which sedimentary manganese deposits were formed.
The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, and precipitation of Mn. To better understand its metallogenetic environment, a detailed study was undertaken involving field observation, mineralogical and geochemical and M?ssbauer spectroscopic analyses. The major findings are as follows:(1) Lithofacies paleogeography, sedimentary structural characteristics, and geochemical indexes indicate that the deposits were formed in an epicontinental marine sedimentary basin environment of normal salinity;(2) there were three ore phases including Mn oxides, Mn carbonates, and mixed Mn ores. The ore minerals found were braunite, manganite, Ca-rhodochrosite, manganocalcite, and kutnahorite. Petrographic and mineralogical information indicates that the metallogenic environment was a weakly alkaline and weakly oxidized to weakly reduced environment, and the mineralization occurred near the redox interface;(3) the V/(V + Ni)ratios, δCe and Fe~(2+)/Fe~(3+) found in profiles of Baigu and Gake ore sections show that the redox conditions of the ore-forming environment were continuously changing; and(4) three Fe species, α-Fe_2O_3, para-Fe~(3+), and para-Fe~(2+),were found in hematite and clay mineral samples using M?ssbauer spectrum analysis. The presence and distribution of these Fe species indicate that the deposit was formed in a typical sedimentary environment during the mineralization process. In summary, our study showed that redox was a key factor controlling the mineralization of the Dounan manganese deposit. Our results have led us to the conclusion that transgression and regression caused fluctuations in sea level, which in turn caused the change of the redox environment. M?ssbauer spectroscopy is an effective tool for studying the redox conditions of the paleoenvironment in which sedimentary manganese deposits were formed.
The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, and precipitation of Mn. To better understand its metallogenetic environment, a detailed study was undertaken involving field observation, mineralogical and geochemical and M?ssbauer spectroscopic analyses. The major findings are as follows:(1) Lithofacies paleogeography, sedimentary structural characteristics, and geochemical indexes indicate that the deposits were formed in an epicontinental marine sedimentary basin environment of normal salinity;(2) there were three ore phases including Mn oxides, Mn carbonates, and mixed Mn ores. The ore minerals found were braunite, manganite, Ca-rhodochrosite, manganocalcite, and kutnahorite. Petrographic and mineralogical information indicates that the metallogenic environment was a weakly alkaline and weakly oxidized to weakly reduced environment, and the mineralization occurred near the redox interface;(3) the V/(V + Ni)ratios, δCe and Fe~(2+)/Fe~(3+) found in profiles of Baigu and Gake ore sections show that the redox conditions of the ore-forming environment were continuously changing; and(4) three Fe species, α-Fe_2O_3, para-Fe~(3+), and para-Fe~(2+),were found in hematite and clay mineral samples using M?ssbauer spectrum analysis. The presence and distribution of these Fe species indicate that the deposit was formed in a typical sedimentary environment during the mineralization process. In summary, our study showed that redox was a key factor controlling the mineralization of the Dounan manganese deposit. Our results have led us to the conclusion that transgression and regression caused fluctuations in sea level, which in turn caused the change of the redox environment. M?ssbauer spectroscopy is an effective tool for studying the redox conditions of the paleoenvironment in which sedimentary manganese deposits were formed.
引文
Ahn JH,Buseck PR(1990)Hematite nanospheres of possible colloidal origin from a Precambrian banded iron formation.Science 250:111-113
Bai WL,Wang XC,Du FY,Yang ZG(2010)The tectonic characteristics and prospecting significance of the Dounan manganese ore belt in Southeast Yunnan.Miner Depos29:35-36(in Chinese)
Banwart SA(1999)Reduction of iron(III)minerals by natural organic matter in groundwater.Geochim Cosmochim Acta63:2919-2928
Berner RA(1981)Authigenic mineral formation resulting from organic matter decomposition in modern sediments.Fortschr Miner 59:117-135
Coey JMD,Schindler DW,Weber F(1974)Iron compounds in lake sediments.Can J Earth Sci 11:1489-1493
DeBaar HJW(1991)On cerium anomalies in the Sargasso sea.Geochim Cosmochim Acta 55:2981-2983
Du QD,Yi HS,Hui B,Li SJ,Xia GQ,Yang W,Wu XF(2013)Recognition,genesis and evolution of manganese ore deposits in southeastern China.Ore Geol Rev 55:99-109
Edwards BD(1985)Bioturbation in a dysaerobic,bathyal basin:California borderland.In:Curran HA(ed)Biogenic structures:their use in interpreting depositional environments,vol 35.Special Publications-SEPM,London,pp 309-331
Hilton J,Long GJ,Chapman JS,Lishman JP(1986)Iron mineralogy in sediments.A Mossbauer study.Geochim Cosmochim Acta50:2147-2151
Hou BH(1994)Primary braunite in Triassic sedimentary manganese deposits of Dounan,Yunnan,China.Ore Geol Rev 9(3):219-239
Hou ZL,Xue ZY,Huang JS,Lin YH et al(1997)The Manganese deposits around the Yangtze platform.Metallurgical Industry Press,Beijing,pp 1-364(in Chinese with English abstract)
Hu XY(2009)Determine themajor element concentrations of carbonate rocks using X-ray fluorescence spectrometry.Acta Miner Sin 598(S):597(in Chinese)
Huang JH,Zhu KJ,Wang KJ,Wang SB,Zhu ZS(1996)Outline of marine Mn deposit in the South China.Contr Geol Miner Resour Res 11(3):9-17(in Chinese with English abstract)
Jones B,Marning DAC(1994)Comparison of geochemical indices used for the interpretation of palaeoredox conditions in mudrocks.Chem Geol 1:111-129
Klein RT,Lohmann KC,Thayer CW(1996)Sr/Ca and13C/12C ratios in skeletal calcite of MytiZus trossulus:covariation with metabolic rate,salinity,and carbon isotopic composition of seawater.Geochim Cosmochim Acta 60:4207-4221
Konhauser KO,Newman DK,Kappler A(2005)The potential significance of microbial Fe(III)reduction during deposition of Precambrian banded iron formations.Geobiology 3(3):167-177
Krauskopf KB(1957)Separation of manganese from iron in sedimentary process.Geochim Cosmochim Acta 2:61-84
Kubo K,Isozaki Y,Matsuo M(1996)Color of bedded chert and redox condition of depositional environment:57Fe Mo¨ssbauer spectroscopic study on chemical state of iron in Triassic deepsea pelagic chert.J Geol Soc Jpn 102:40-48(in Japanese with English abstract)
Kuno A,Matsuo M,Takano B(1998)Mo¨ssbauer spectroscopic study on vertical distribution of iron components in estuarine sediments collected from Tama River in Tokyo.Hyperfine Interact C3:328-331
Li SJ,Yi HS,Ma X,Xia GQ,Rong JF,Da XJ(2009)Sedimentary facies of the manganese-bearing strata in the Falang Formation,southeastern Yunnan.Sediment Geol Tethyan Geol 29(2):33-38(in Chinese with English abstract)
Liu et al(1984)Typical deposit research report of Dounan manganese deposits,Yanshan County,Yunnan Province.Geol Miner Bur Yunnan Prov 86:1-106(in Chinese)
Liu HJ,Xue YZ(1999)Sedimentology of Triassic Dounan-type manganese deposits,western margin,Yangtze platform,China.Ore Geol Rev 15:165-176
Liu RF,Tian BK,Shi ZZ,Hao RX,Li HC(1988)Geochemical characteristics of the Mn bearing-Falang formation in the Southeast Yunnan Province.Contr Geol Miner Resour Res3(4):1-19(in Chinese with English abstract)
Luo CX,Du ZY(1992)Lithofacies palaeogeography and ore-forming condition of main ore-bearing strata of the middle to late Triassic manganese resources at South margin of the upper Yangtze.Bull Chengdu Inst Geol Miner Resour Chin Acad Geol Sci16:137-159
Manning PG,Ash LA(1979)Mo¨ssbauer spectral studies of pyrite,ferric and high-spin ferrous distributions in sulfide rich sediments from Moira Lake,Ontario.Can Miner 17:111-115
Matsuo M,Takano B,Sugimori K(1996)57Fe Mossbauer spectroscopic study of estuarine sediments taken from the Tama River in Tokyo.In:II Nuovo Cimento(Conf.Proc.),vol 50,pp 757-760
Morris RC,Horwitz RC(1983)The origin of the iron-formation-rich Hamersley group of western Australia-deposition on a platform.Precambr Res 21:273-297
Murray RW,Buchholtzten Brink MR,Jones DL,Gerlach DC,Price Russ III(1990)Rare earth elements as indicators of different marine depositional environments.Geology 18:268-271
Qi L,Hu JD,Conrad G(2000)Determination of trace elements in granites by inductively coupled plasma mass spectrometry.Talanta 51(3):507-513
Rasmussen B,Krape B,Meier DB(2014)Replacement origin for hematite in 2.5 Ga banded iron formation:evidence for postdepositional oxidation of iron-bearing minerals.Geol Soc Am Bull126:438-446
Roy S(2006)Sedimentary manganese metallogenesis in response to the evolution of the Earth system.Earth Sci Rev 77:273-305
Sholkovitz ER,Schneider DL(1991)Cerium redox cycles and rare earth elements in the Sargasso Sea.Geochim Cosmochim Acta55:2737-2743
Stevens JG,Khasanov AM,Miller JW,Pollak H,Li Z(eds)(1998)In:Mo¨ssbauer mineral handbook,Mo¨ssbauer effect data centre.University of North Carolina,Asheville,p 527
Su JH(1983)Dounan manganese deposit:a braunite deposit of sedimentary origin.Bull Inst Miner Depos Chin Acad Geol Sci4:3-49(in Chinese with English abstract)
Sun S,Li YL(2017)Geneses and evolutions of iron-bearing minerals in banded iron formations of[3760 to ca.2200 million-yearold:constraints from electron microscopic,X-ray diffraction and Mo¨ssbauer spectroscopic investigations.Precambr Res 289:1-17
Sun S,Konhauser KO,Kappler A,Li YL(2015)Primary hematite in Neoarchean to Paleoproterozoic oceans.Geol Soc Am Bull127:850-861
Tang YF,Yi HS(2011)Mineral phase changes and depositional model of sedimentary manganese deposits in Dounan area of southeastern Yunnan.Geol China 38(2):451-461(in Chinese with English abstract)
Tribovillard N,Algeo TJ,Lyonsc T,Riboulleau A(2006)Trace metals as paleoredox and paleoproductivity proxies:an update.Chem Geol 232:12-32
Tuccillo MA,Cozzarelli IM,Herman JS(1999)Iron reduction in the sediments of a hydrocarbon-contaminated.Appl Geochem14:655-667
Tyson RV,Pearson TH(1991)Modern and ancient continental shelf anoxia:an overview.In:Tyson RV,Pearson TH(eds)Modern and ancient continental shelf anoxia,vol 58.Geological Society Special Publications,London,pp 1-26
Waander FB,Waanders Silva LO,Saikia BK(2017)The use of Mossbauer spectroscopy in environmental research.Hyperfine Interact 238:52
Wedepohl KH(1971)Environmental influences on the chemical composition of shales and clays.In:Ahrens LH,Press F,Runcorn SK,Urey HC(eds)Physics and chemistry of the earth.Pergamon,Oxford,pp 305-333
Wedepohl KH(1991)The composition of the upper Earth’s crust and the natural cycles of selected metals.In:Merian E(ed)Metals and their compounds in the environment.VCH-Verlagsgesellschaft,Weinheim,pp 3-17
Wignall PB(1994)Black shale.Clarendon Press,Oxford,pp 1-127
Wu YL,Zhu HF(1994)Triassic lithofacies palaeogeography and mineralization in southern China.Geological Publishing House,Beijing,pp 99-103(in Chinese)
Xia GQ,Yi HS,Li SJ,Wu XF(2010)Research on manganeseaccumulation features in Middle Triassic Ladinian sedimentary system and sequence stratigraphic framework,Southeast Yunnan.Geol Rev 56(5):703-709(in Chinese with English abstract)
Zheng RC,Zhang JQ(1991)Gravity flow manganese deposits and their sedimentary environments in Middle Triassic from Dounan,Southeast Yunnan.Chengdu Coll Geol 18(4):65-75(in Chinese)
Zheng GD,Takano B,Kuno A,Katsuo M(2001)Iron speciation in modern sediment from Erhai lake,southwestern China:redox condition in an ancient environment.Appl Geochem16:1201-1203
Zheng GD,Fu BH,Takahashi Y,Kuno A,Matsuo M,Zhang JD(2010)Chemical speciation of redox sensitive elements during hydrocarbon leaching in the Junggar Basin,Northwest China.J Asian Earth Sci 39:713-723
Zhong JT(1986)Metallogeny of the Dounan manganese deposit.Geol Rev 32(6):583-588(in Chinese with English abstract)
Zhu XK,Peng QY,Zhang RB,An ZZ,Zhang FF,Yan B,Li J,Gao ZF,Tan Y,Pan W(2013)Geological and geochemical characteristics of the Daotuo super-large manganese ore deposit at Songtao County in Guizhou Province.Acta Geol Sin87(09):1335-1348(in Chinese with English abstract)
Bai WL,Wang XC,Du FY,Yang ZG(2010)The tectonic characteristics and prospecting significance of the Dounan manganese ore belt in Southeast Yunnan.Miner Depos29:35-36(in Chinese)
Banwart SA(1999)Reduction of iron(III)minerals by natural organic matter in groundwater.Geochim Cosmochim Acta63:2919-2928
Berner RA(1981)Authigenic mineral formation resulting from organic matter decomposition in modern sediments.Fortschr Miner 59:117-135
Coey JMD,Schindler DW,Weber F(1974)Iron compounds in lake sediments.Can J Earth Sci 11:1489-1493
DeBaar HJW(1991)On cerium anomalies in the Sargasso sea.Geochim Cosmochim Acta 55:2981-2983
Du QD,Yi HS,Hui B,Li SJ,Xia GQ,Yang W,Wu XF(2013)Recognition,genesis and evolution of manganese ore deposits in southeastern China.Ore Geol Rev 55:99-109
Edwards BD(1985)Bioturbation in a dysaerobic,bathyal basin:California borderland.In:Curran HA(ed)Biogenic structures:their use in interpreting depositional environments,vol 35.Special Publications-SEPM,London,pp 309-331
Hilton J,Long GJ,Chapman JS,Lishman JP(1986)Iron mineralogy in sediments.A Mossbauer study.Geochim Cosmochim Acta50:2147-2151
Hou BH(1994)Primary braunite in Triassic sedimentary manganese deposits of Dounan,Yunnan,China.Ore Geol Rev 9(3):219-239
Hou ZL,Xue ZY,Huang JS,Lin YH et al(1997)The Manganese deposits around the Yangtze platform.Metallurgical Industry Press,Beijing,pp 1-364(in Chinese with English abstract)
Hu XY(2009)Determine themajor element concentrations of carbonate rocks using X-ray fluorescence spectrometry.Acta Miner Sin 598(S):597(in Chinese)
Huang JH,Zhu KJ,Wang KJ,Wang SB,Zhu ZS(1996)Outline of marine Mn deposit in the South China.Contr Geol Miner Resour Res 11(3):9-17(in Chinese with English abstract)
Jones B,Marning DAC(1994)Comparison of geochemical indices used for the interpretation of palaeoredox conditions in mudrocks.Chem Geol 1:111-129
Klein RT,Lohmann KC,Thayer CW(1996)Sr/Ca and13C/12C ratios in skeletal calcite of MytiZus trossulus:covariation with metabolic rate,salinity,and carbon isotopic composition of seawater.Geochim Cosmochim Acta 60:4207-4221
Konhauser KO,Newman DK,Kappler A(2005)The potential significance of microbial Fe(III)reduction during deposition of Precambrian banded iron formations.Geobiology 3(3):167-177
Krauskopf KB(1957)Separation of manganese from iron in sedimentary process.Geochim Cosmochim Acta 2:61-84
Kubo K,Isozaki Y,Matsuo M(1996)Color of bedded chert and redox condition of depositional environment:57Fe Mo¨ssbauer spectroscopic study on chemical state of iron in Triassic deepsea pelagic chert.J Geol Soc Jpn 102:40-48(in Japanese with English abstract)
Kuno A,Matsuo M,Takano B(1998)Mo¨ssbauer spectroscopic study on vertical distribution of iron components in estuarine sediments collected from Tama River in Tokyo.Hyperfine Interact C3:328-331
Li SJ,Yi HS,Ma X,Xia GQ,Rong JF,Da XJ(2009)Sedimentary facies of the manganese-bearing strata in the Falang Formation,southeastern Yunnan.Sediment Geol Tethyan Geol 29(2):33-38(in Chinese with English abstract)
Liu et al(1984)Typical deposit research report of Dounan manganese deposits,Yanshan County,Yunnan Province.Geol Miner Bur Yunnan Prov 86:1-106(in Chinese)
Liu HJ,Xue YZ(1999)Sedimentology of Triassic Dounan-type manganese deposits,western margin,Yangtze platform,China.Ore Geol Rev 15:165-176
Liu RF,Tian BK,Shi ZZ,Hao RX,Li HC(1988)Geochemical characteristics of the Mn bearing-Falang formation in the Southeast Yunnan Province.Contr Geol Miner Resour Res3(4):1-19(in Chinese with English abstract)
Luo CX,Du ZY(1992)Lithofacies palaeogeography and ore-forming condition of main ore-bearing strata of the middle to late Triassic manganese resources at South margin of the upper Yangtze.Bull Chengdu Inst Geol Miner Resour Chin Acad Geol Sci16:137-159
Manning PG,Ash LA(1979)Mo¨ssbauer spectral studies of pyrite,ferric and high-spin ferrous distributions in sulfide rich sediments from Moira Lake,Ontario.Can Miner 17:111-115
Matsuo M,Takano B,Sugimori K(1996)57Fe Mossbauer spectroscopic study of estuarine sediments taken from the Tama River in Tokyo.In:II Nuovo Cimento(Conf.Proc.),vol 50,pp 757-760
Morris RC,Horwitz RC(1983)The origin of the iron-formation-rich Hamersley group of western Australia-deposition on a platform.Precambr Res 21:273-297
Murray RW,Buchholtzten Brink MR,Jones DL,Gerlach DC,Price Russ III(1990)Rare earth elements as indicators of different marine depositional environments.Geology 18:268-271
Qi L,Hu JD,Conrad G(2000)Determination of trace elements in granites by inductively coupled plasma mass spectrometry.Talanta 51(3):507-513
Rasmussen B,Krape B,Meier DB(2014)Replacement origin for hematite in 2.5 Ga banded iron formation:evidence for postdepositional oxidation of iron-bearing minerals.Geol Soc Am Bull126:438-446
Roy S(2006)Sedimentary manganese metallogenesis in response to the evolution of the Earth system.Earth Sci Rev 77:273-305
Sholkovitz ER,Schneider DL(1991)Cerium redox cycles and rare earth elements in the Sargasso Sea.Geochim Cosmochim Acta55:2737-2743
Stevens JG,Khasanov AM,Miller JW,Pollak H,Li Z(eds)(1998)In:Mo¨ssbauer mineral handbook,Mo¨ssbauer effect data centre.University of North Carolina,Asheville,p 527
Su JH(1983)Dounan manganese deposit:a braunite deposit of sedimentary origin.Bull Inst Miner Depos Chin Acad Geol Sci4:3-49(in Chinese with English abstract)
Sun S,Li YL(2017)Geneses and evolutions of iron-bearing minerals in banded iron formations of[3760 to ca.2200 million-yearold:constraints from electron microscopic,X-ray diffraction and Mo¨ssbauer spectroscopic investigations.Precambr Res 289:1-17
Sun S,Konhauser KO,Kappler A,Li YL(2015)Primary hematite in Neoarchean to Paleoproterozoic oceans.Geol Soc Am Bull127:850-861
Tang YF,Yi HS(2011)Mineral phase changes and depositional model of sedimentary manganese deposits in Dounan area of southeastern Yunnan.Geol China 38(2):451-461(in Chinese with English abstract)
Tribovillard N,Algeo TJ,Lyonsc T,Riboulleau A(2006)Trace metals as paleoredox and paleoproductivity proxies:an update.Chem Geol 232:12-32
Tuccillo MA,Cozzarelli IM,Herman JS(1999)Iron reduction in the sediments of a hydrocarbon-contaminated.Appl Geochem14:655-667
Tyson RV,Pearson TH(1991)Modern and ancient continental shelf anoxia:an overview.In:Tyson RV,Pearson TH(eds)Modern and ancient continental shelf anoxia,vol 58.Geological Society Special Publications,London,pp 1-26
Waander FB,Waanders Silva LO,Saikia BK(2017)The use of Mossbauer spectroscopy in environmental research.Hyperfine Interact 238:52
Wedepohl KH(1971)Environmental influences on the chemical composition of shales and clays.In:Ahrens LH,Press F,Runcorn SK,Urey HC(eds)Physics and chemistry of the earth.Pergamon,Oxford,pp 305-333
Wedepohl KH(1991)The composition of the upper Earth’s crust and the natural cycles of selected metals.In:Merian E(ed)Metals and their compounds in the environment.VCH-Verlagsgesellschaft,Weinheim,pp 3-17
Wignall PB(1994)Black shale.Clarendon Press,Oxford,pp 1-127
Wu YL,Zhu HF(1994)Triassic lithofacies palaeogeography and mineralization in southern China.Geological Publishing House,Beijing,pp 99-103(in Chinese)
Xia GQ,Yi HS,Li SJ,Wu XF(2010)Research on manganeseaccumulation features in Middle Triassic Ladinian sedimentary system and sequence stratigraphic framework,Southeast Yunnan.Geol Rev 56(5):703-709(in Chinese with English abstract)
Zheng RC,Zhang JQ(1991)Gravity flow manganese deposits and their sedimentary environments in Middle Triassic from Dounan,Southeast Yunnan.Chengdu Coll Geol 18(4):65-75(in Chinese)
Zheng GD,Takano B,Kuno A,Katsuo M(2001)Iron speciation in modern sediment from Erhai lake,southwestern China:redox condition in an ancient environment.Appl Geochem16:1201-1203
Zheng GD,Fu BH,Takahashi Y,Kuno A,Matsuo M,Zhang JD(2010)Chemical speciation of redox sensitive elements during hydrocarbon leaching in the Junggar Basin,Northwest China.J Asian Earth Sci 39:713-723
Zhong JT(1986)Metallogeny of the Dounan manganese deposit.Geol Rev 32(6):583-588(in Chinese with English abstract)
Zhu XK,Peng QY,Zhang RB,An ZZ,Zhang FF,Yan B,Li J,Gao ZF,Tan Y,Pan W(2013)Geological and geochemical characteristics of the Daotuo super-large manganese ore deposit at Songtao County in Guizhou Province.Acta Geol Sin87(09):1335-1348(in Chinese with English abstract)