龙门山甘溪泥盆系养马坝组铁质鲕粒地球化学特征与成因
|
摘要
研究龙门山地区甘溪剖面中泥盆统养马坝组铁质鲕粒的成因机制和沉积环境。以薄片鉴定和扫描电镜分析为基础,通过主元素、痕量元素和稀土元素测试,对铁质鲕粒的地球化学特征进行了分析,进而对铁质的来源和铁质鲕粒的成因进行了研究。甘溪的养马坝组铁质鲕粒有正常鲕粒、绿泥石鲕粒和铁化鲕粒3种类型,鲕粒中主要的含铁矿物为赤铁矿和绿泥石。养马坝组铁质鲕粒SiO_2、Al_2O_3和TiO_2彼此之间均存在正相关关系,并且具有较高的相关系数。As平均质量分数为4.1×10~(-6),与正常海水的As相近;(As+Cu+Mo+Pb+V+Zn)-(Ni+Co)和(Co+Ni+Cu)-(Co/Zn)图表明养马坝组铁质鲕粒中的铁质来源于陆源风化物质。δCe、Eu和La_N/Yb_N平均值分别为1.26、1.29和0.414,均处于大陆边缘沉积范围内。养马坝组铁质鲕粒形成于温暖潮湿动荡的滨浅海环境。
The Middle Devonian Yangmaba Formation ferruginous oolites in the Longmenshan area represent an important form of the "Ningxiang-style" oolitic hematite deposits in China. Based on the microscopic identification and SEM analysis, combined with the study of geochemical characteristics of these ferruginous oolites, including their major elements, trace elements and rare earth elements, the Yangmaba Formation ferruginous oolites are studied in order to understand their genetic mechanism and sedimentary environment. It shows that the ferruginous oolites can be decided into normal oolites, chloritic oolites and ferritic oolites, and the iron-bearing minerals of these oolites are mainly hematite and chlorite. Geochemical analysis reveals that the constant elements in these oolites are SiO_2, Al_2O_3 and TiO_2, which have significant positive correlation with each other. The average mass fraction of trace elements in these oolites is 4.1×10~(-6), similar to those in seawater.(As+Cu+Mo+Pb+V+Zn)-(Ni+Co) plot and(Co+Ni+Cu)-(Co/Zn) plot indicate that the ferric elements in these oolites are deposited in a terrestrial weathering environment. The average contents of rare earth elements δCe, Eu and La_N/Yb_N are 1.26, 1.29 and 0.414, respectively, referring to a continental margin environment. Geochemical analysis of the Yangmaba ferruginous oolites from the Shigouli outcrop section in the Longmenshan area indicates that the ferric elements in these oolites are resulted from terrestrial weathering, and these oolites are formed in a warm and humid subtidal environment with relatively strong energy.
The Middle Devonian Yangmaba Formation ferruginous oolites in the Longmenshan area represent an important form of the "Ningxiang-style" oolitic hematite deposits in China. Based on the microscopic identification and SEM analysis, combined with the study of geochemical characteristics of these ferruginous oolites, including their major elements, trace elements and rare earth elements, the Yangmaba Formation ferruginous oolites are studied in order to understand their genetic mechanism and sedimentary environment. It shows that the ferruginous oolites can be decided into normal oolites, chloritic oolites and ferritic oolites, and the iron-bearing minerals of these oolites are mainly hematite and chlorite. Geochemical analysis reveals that the constant elements in these oolites are SiO_2, Al_2O_3 and TiO_2, which have significant positive correlation with each other. The average mass fraction of trace elements in these oolites is 4.1×10~(-6), similar to those in seawater.(As+Cu+Mo+Pb+V+Zn)-(Ni+Co) plot and(Co+Ni+Cu)-(Co/Zn) plot indicate that the ferric elements in these oolites are deposited in a terrestrial weathering environment. The average contents of rare earth elements δCe, Eu and La_N/Yb_N are 1.26, 1.29 and 0.414, respectively, referring to a continental margin environment. Geochemical analysis of the Yangmaba ferruginous oolites from the Shigouli outcrop section in the Longmenshan area indicates that the ferric elements in these oolites are resulted from terrestrial weathering, and these oolites are formed in a warm and humid subtidal environment with relatively strong energy.
引文
[1] 周家云,郑荣才,张裕书,等.华南泥盆纪古地理环境对宁乡式铁矿床时空分布、矿石特征的制约[J].地质科技情报,2009,28(1):93-98.Zhou J Y,Zheng R C,Zhang Y S,et al.Constraints of South China Devonian Ningxiang palaeogeography on the temporal and spatial distribution of iron ore deposits and their characteristics[J].Geological Science and Technology Information,2009,28(1):93-98.(in Chinese)
[2] 廖士范,魏梁鸿,刘成德,等.中国泥盆纪鲕铁石沉积环境、成因[J].沉积学报,1993,11(1):93-102.Liao S F,Wei L H,Liu C D,et al.Sedimentary environments and origin of the Devonian oolitic ironstones in China[J].Acta Sedimentologica Sinica,1993,11(1):93-102.(in Chinese)
[3] 惠博.鄂西宁乡式铁矿沉积特征及成因[D].成都:成都理工大学档案馆,2014:25-31.Hui B.The Sedimentary Characteristics and Genesis of the Ningxiang Type Iron Ore in West Hubei[D].Chengdu:The Archive of Chengdu University of Technology,2014:25-31.(in Chinese)
[4] 赵一鸣,毕承思.宁乡式沉积铁矿床的时空分布和演化[J].矿床地质,2000,19(4):350-362.Zhao Y M,Bi C S.Time-space distribution and evolution of the Ningxiang type sedimentary iron deposits[J].Mineral Deposits,2000,19(4):350-362.(in Chinese)
[5] Utescher T.A sedimentological study of Fe-oolite bearing carbonate rocks at the Lower-Middle Devonian boundary in the western Rhenish Schiefergebirge[J].Neues Jahrbuch fur Geologie und Palaontologie Monatshefte,1992,(5):303-320.
[6] 戴永定,宋海明,沈继英.河北宣龙铁矿化石细菌[J].中国科学:D辑,2003,33(8):751-759.Dai Y D,Song H M,Shen J Y.Fossil bacteria in Xuanlong iron deposits,Hebei[J].Science in China:Series D,2003,33(8):751-759.(in Chinese)
[7] 祝新友,王京彬,王艳丽,等.宁乡式铁矿成因新解——后生热液成因的地质与地球化学证据[J].矿产勘查,2015,6(1):7-16.Zhu X Y,Wang J B,Wang Y L,et al.Study on genesis of Ningxiang type (Clinton type) iron deposit,Hunan[J].Mineral Exploration,2015,6(1):7-16.(in Chinese)
[8] 朱继存.宁乡式铁矿床成因的新认识[J].合肥工业大学学报(自然科学版),2001,24(1):143-146.Zhu J C.New views on the genesis of Ningxiang-type iron deposit[J].Journal of Hefei University of Technology (Natural Sciences),2001,24(1):143-146.(in Chinese)
[9] 丘达光.广西“宁乡式”铁矿中绿泥石鲕粒的特征及成因[J].矿物岩石地球化学通报,1991,10(3):146-148.Qiu D G.Characteristics and genesis of chlorite oolitic in “Ningxiang type” iron ore in Guangxi[J].Bulletin of Mineralogy,Petrology and Geochemistry,1991,10(3):146-148.(in Chinese)
[10] 丘达光.桂东北“宁乡式”铁矿中赤铁矿鲕粒成因的新认识[J].矿物岩石地球化学通报,1991,10(3):148-150.Qiu D G.New understanding of the origin of hematite oolitic in “Ningxiang type” iron ore in Northeast Guangxi[J].Bulletin of Mineralogy,Petrology and Geochemistry,1991,10(3):148-150.(in Chinese)
[11] 李朋威,周川闽,金廷福,等.太原西山七里沟剖面本溪组铁质鲕粒成因探讨[J].沉积学报,2013,31(3):396-403.Li P W,Zhou C M,Jin T F,et al.Origin of the ferriferous ooids in the Benxi Formation at the Qiligou Section,Taiyuan Xishan[J].Acta Sedimentologica Sinica,2013,31(3):396-403.(in Chinese)
[12] 侯鸿飞,万正权,鲜思远.四川龙门山地区泥盆纪地层古生物及沉积相[M].北京:地质出版社,1988.Hou H F,Wan Z Q,Xian S Y.Devonian Stratigraphy,Paleontology and Sedimentary Facies of Longmenshan,Sichuan[M].Beijing:Geological Publishing House,1988.(in Chinese)
[13] 郑荣才,文华国,王昌勇,等.龙门山泥盆系野外实习指南[M].北京:地质出版社,2016.Zheng R C,Wen H G,Wang C Y,et al.Guide to the Field Practice of the Devonian in Longmen Mountain[M].Beijing:Geological Publishing House,2016.(in Chinese)
[14] 刘文均,陈源仁,郑荣才.龙门山地区泥盆纪层序地层划分、对比和海平面相对变化[C]//层序地层.成都:成都科技大学出版社,1996:1-11.Liu W J,Chen Y R,Zheng R C.Devonian sequence stratigraphy and relative sea-level changes in Longmenshan area,Sichuan[C]//Sequence Stratigraphy.Chengdu:Chengdu University of Science and Technology Press,1996:1-11.(in Chinese)
[15] 李祥辉,刘文均,郑荣才.龙门山地区泥盆纪碳酸盐与硅质碎屑的混积相与混积机理[J].岩相古地理,1997,17(3):339-344.Li X H,Liu W J,Zheng R C.Hybird facies and mechanism for the formation of the mixed Devonian carbonate-siliciclastic sediments in the Longmen Mountain area,Sichuan[J].Sedimentary Facies and Palaeogeography,1997,17(3):339-344.(in Chinese)
[16] Baioumy H,Omran M,Fabritius T.Mineralogy,geochemistry and the origin of high-phosphorus oolitic iron ores of Aswan,Egypt[J].Ore Geology Reviews,2017,80:185-199.
[17] 毛玲玲,伊海生,季长军,等.柴达木盆地新生代湖相碳酸盐岩岩石学及碳氧同位素特征[J].地质科技情报,2014,33(1):41-48.Mao L L,Yi H S,Ji C J,et al.Petrography and carbon-oxygen isotope characteristics of the Cenozoic lacustrine carbonate rocks in Qaidam Basin[J].Geological Science and Technology Information,2014,33(1):41-48.(in Chinese)
[18] Hatch J R,Leventhal J S.Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian (Missourian) Stark Shale Member of the Dennis Limestone,Wabaunsee County,Kansas,U.S.A.[J].Chemical Geology,1992,99(1/3):65-82.
[19] Marchig V,Gundlach H,Moller P,et al.Some geological indicators for discrimination between diagenetic and hydrothermal metalliferous sediments[J].Marine Geology,1982,50(3):241-256.
[20] 李凤杰,刘殿鹤,刘琪.四川宣汉地区吴家坪组硅质岩地化特征及其成因探讨[J].天然气地球科学,2010,21(1):62-67.Li F J,Liu D H,Liu Q.Geochemical characteristics and genesis discussion of Wujiaping Formation siliceous rocks outcrop in Xuanhan area of Sichuan[J].Natural Gas Geoscience,2010,21(1):62-67.(in Chinese)
[21] Nicholson K.Contrasting mineralogical-geochemical signatures of manganese oxides:Guides to metallogenesis[J].Economic Geology,1992,87:1253-1264.
[22] Toth J R.Deposition of submarine crusts rich in manganese and iron[J].Geological Society of America Bulletin,1980,91:44-54.
[23] Douville E,Bienvenu P,Charlou J L,et al.Rare earth elements in fluids from various deep-sea hydrothermal systems[J].Geochimica et Cosmochimica Acta,1999,63:627-643.
[24] German C R,Hergt J,Palmer M R,et al.Geochemistry of a hydrothermal sediment core from the OBS vent-field,21°N East Pacific Rise[J].Chemical Geology,1999,155:65-75.
[25] Holser W T.Evaluation of the application of rare-earth elements to paleoceanography[J].Palaeogeography Palaeoclimatology Palaeoecology,1997,132:309-323.
[26] Murray R W.Chemical criteria to identify the depositional environment of chert:General principles and application[J].Sedimentary Geology,1994,90:213-232.
[27] Murray R W,Buchholtz ten Brink M R,Gerlach D C,et al.Rare earth,major,and trace elements in chert from the Franciscan complex and Monterey group,Californian:Assessing REE sources to fine-grained marine sediments[J].Geochimica et Cosmochimica Acta,1991,55:1875-1895.
[28] 李祥辉,刘文均,郑荣才.龙门山地区泥盆纪海平面升降规程、频幅及对比[J].成都理工学院学报,1998,25(4):495-502.Li X H,Liu W J,Zheng R C.Frequency,amplitude,and pattern of sea-level changes in Devonian in Longmen mountains,western Yangtze[J].Journal of Chengdu University of Technology,1998,25(4):495-502.(in Chinese)
[29] 张扬,郄文昆,李益龙,等.四川龙门山石炭纪鲕状赤铁矿及其古环境意义[J].岩石矿物学杂志,2009,28(1):51-57.Zhang Y,Xi W K,Li Y L,et al.Carboniferous oolitic hematite in Longmenshan area of Sichuan Province and its paleoenvironmental significance[J].Acta Petrologica et Mineralogica,2009,28(1):51-57.(in Chinese)
[30] Gygi R A.Oolitic iron formations:Marine or not marine[J].Eclogae Geologicae Helvetiae,1981,74:233-254.
[2] 廖士范,魏梁鸿,刘成德,等.中国泥盆纪鲕铁石沉积环境、成因[J].沉积学报,1993,11(1):93-102.Liao S F,Wei L H,Liu C D,et al.Sedimentary environments and origin of the Devonian oolitic ironstones in China[J].Acta Sedimentologica Sinica,1993,11(1):93-102.(in Chinese)
[3] 惠博.鄂西宁乡式铁矿沉积特征及成因[D].成都:成都理工大学档案馆,2014:25-31.Hui B.The Sedimentary Characteristics and Genesis of the Ningxiang Type Iron Ore in West Hubei[D].Chengdu:The Archive of Chengdu University of Technology,2014:25-31.(in Chinese)
[4] 赵一鸣,毕承思.宁乡式沉积铁矿床的时空分布和演化[J].矿床地质,2000,19(4):350-362.Zhao Y M,Bi C S.Time-space distribution and evolution of the Ningxiang type sedimentary iron deposits[J].Mineral Deposits,2000,19(4):350-362.(in Chinese)
[5] Utescher T.A sedimentological study of Fe-oolite bearing carbonate rocks at the Lower-Middle Devonian boundary in the western Rhenish Schiefergebirge[J].Neues Jahrbuch fur Geologie und Palaontologie Monatshefte,1992,(5):303-320.
[6] 戴永定,宋海明,沈继英.河北宣龙铁矿化石细菌[J].中国科学:D辑,2003,33(8):751-759.Dai Y D,Song H M,Shen J Y.Fossil bacteria in Xuanlong iron deposits,Hebei[J].Science in China:Series D,2003,33(8):751-759.(in Chinese)
[7] 祝新友,王京彬,王艳丽,等.宁乡式铁矿成因新解——后生热液成因的地质与地球化学证据[J].矿产勘查,2015,6(1):7-16.Zhu X Y,Wang J B,Wang Y L,et al.Study on genesis of Ningxiang type (Clinton type) iron deposit,Hunan[J].Mineral Exploration,2015,6(1):7-16.(in Chinese)
[8] 朱继存.宁乡式铁矿床成因的新认识[J].合肥工业大学学报(自然科学版),2001,24(1):143-146.Zhu J C.New views on the genesis of Ningxiang-type iron deposit[J].Journal of Hefei University of Technology (Natural Sciences),2001,24(1):143-146.(in Chinese)
[9] 丘达光.广西“宁乡式”铁矿中绿泥石鲕粒的特征及成因[J].矿物岩石地球化学通报,1991,10(3):146-148.Qiu D G.Characteristics and genesis of chlorite oolitic in “Ningxiang type” iron ore in Guangxi[J].Bulletin of Mineralogy,Petrology and Geochemistry,1991,10(3):146-148.(in Chinese)
[10] 丘达光.桂东北“宁乡式”铁矿中赤铁矿鲕粒成因的新认识[J].矿物岩石地球化学通报,1991,10(3):148-150.Qiu D G.New understanding of the origin of hematite oolitic in “Ningxiang type” iron ore in Northeast Guangxi[J].Bulletin of Mineralogy,Petrology and Geochemistry,1991,10(3):148-150.(in Chinese)
[11] 李朋威,周川闽,金廷福,等.太原西山七里沟剖面本溪组铁质鲕粒成因探讨[J].沉积学报,2013,31(3):396-403.Li P W,Zhou C M,Jin T F,et al.Origin of the ferriferous ooids in the Benxi Formation at the Qiligou Section,Taiyuan Xishan[J].Acta Sedimentologica Sinica,2013,31(3):396-403.(in Chinese)
[12] 侯鸿飞,万正权,鲜思远.四川龙门山地区泥盆纪地层古生物及沉积相[M].北京:地质出版社,1988.Hou H F,Wan Z Q,Xian S Y.Devonian Stratigraphy,Paleontology and Sedimentary Facies of Longmenshan,Sichuan[M].Beijing:Geological Publishing House,1988.(in Chinese)
[13] 郑荣才,文华国,王昌勇,等.龙门山泥盆系野外实习指南[M].北京:地质出版社,2016.Zheng R C,Wen H G,Wang C Y,et al.Guide to the Field Practice of the Devonian in Longmen Mountain[M].Beijing:Geological Publishing House,2016.(in Chinese)
[14] 刘文均,陈源仁,郑荣才.龙门山地区泥盆纪层序地层划分、对比和海平面相对变化[C]//层序地层.成都:成都科技大学出版社,1996:1-11.Liu W J,Chen Y R,Zheng R C.Devonian sequence stratigraphy and relative sea-level changes in Longmenshan area,Sichuan[C]//Sequence Stratigraphy.Chengdu:Chengdu University of Science and Technology Press,1996:1-11.(in Chinese)
[15] 李祥辉,刘文均,郑荣才.龙门山地区泥盆纪碳酸盐与硅质碎屑的混积相与混积机理[J].岩相古地理,1997,17(3):339-344.Li X H,Liu W J,Zheng R C.Hybird facies and mechanism for the formation of the mixed Devonian carbonate-siliciclastic sediments in the Longmen Mountain area,Sichuan[J].Sedimentary Facies and Palaeogeography,1997,17(3):339-344.(in Chinese)
[16] Baioumy H,Omran M,Fabritius T.Mineralogy,geochemistry and the origin of high-phosphorus oolitic iron ores of Aswan,Egypt[J].Ore Geology Reviews,2017,80:185-199.
[17] 毛玲玲,伊海生,季长军,等.柴达木盆地新生代湖相碳酸盐岩岩石学及碳氧同位素特征[J].地质科技情报,2014,33(1):41-48.Mao L L,Yi H S,Ji C J,et al.Petrography and carbon-oxygen isotope characteristics of the Cenozoic lacustrine carbonate rocks in Qaidam Basin[J].Geological Science and Technology Information,2014,33(1):41-48.(in Chinese)
[18] Hatch J R,Leventhal J S.Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian (Missourian) Stark Shale Member of the Dennis Limestone,Wabaunsee County,Kansas,U.S.A.[J].Chemical Geology,1992,99(1/3):65-82.
[19] Marchig V,Gundlach H,Moller P,et al.Some geological indicators for discrimination between diagenetic and hydrothermal metalliferous sediments[J].Marine Geology,1982,50(3):241-256.
[20] 李凤杰,刘殿鹤,刘琪.四川宣汉地区吴家坪组硅质岩地化特征及其成因探讨[J].天然气地球科学,2010,21(1):62-67.Li F J,Liu D H,Liu Q.Geochemical characteristics and genesis discussion of Wujiaping Formation siliceous rocks outcrop in Xuanhan area of Sichuan[J].Natural Gas Geoscience,2010,21(1):62-67.(in Chinese)
[21] Nicholson K.Contrasting mineralogical-geochemical signatures of manganese oxides:Guides to metallogenesis[J].Economic Geology,1992,87:1253-1264.
[22] Toth J R.Deposition of submarine crusts rich in manganese and iron[J].Geological Society of America Bulletin,1980,91:44-54.
[23] Douville E,Bienvenu P,Charlou J L,et al.Rare earth elements in fluids from various deep-sea hydrothermal systems[J].Geochimica et Cosmochimica Acta,1999,63:627-643.
[24] German C R,Hergt J,Palmer M R,et al.Geochemistry of a hydrothermal sediment core from the OBS vent-field,21°N East Pacific Rise[J].Chemical Geology,1999,155:65-75.
[25] Holser W T.Evaluation of the application of rare-earth elements to paleoceanography[J].Palaeogeography Palaeoclimatology Palaeoecology,1997,132:309-323.
[26] Murray R W.Chemical criteria to identify the depositional environment of chert:General principles and application[J].Sedimentary Geology,1994,90:213-232.
[27] Murray R W,Buchholtz ten Brink M R,Gerlach D C,et al.Rare earth,major,and trace elements in chert from the Franciscan complex and Monterey group,Californian:Assessing REE sources to fine-grained marine sediments[J].Geochimica et Cosmochimica Acta,1991,55:1875-1895.
[28] 李祥辉,刘文均,郑荣才.龙门山地区泥盆纪海平面升降规程、频幅及对比[J].成都理工学院学报,1998,25(4):495-502.Li X H,Liu W J,Zheng R C.Frequency,amplitude,and pattern of sea-level changes in Devonian in Longmen mountains,western Yangtze[J].Journal of Chengdu University of Technology,1998,25(4):495-502.(in Chinese)
[29] 张扬,郄文昆,李益龙,等.四川龙门山石炭纪鲕状赤铁矿及其古环境意义[J].岩石矿物学杂志,2009,28(1):51-57.Zhang Y,Xi W K,Li Y L,et al.Carboniferous oolitic hematite in Longmenshan area of Sichuan Province and its paleoenvironmental significance[J].Acta Petrologica et Mineralogica,2009,28(1):51-57.(in Chinese)
[30] Gygi R A.Oolitic iron formations:Marine or not marine[J].Eclogae Geologicae Helvetiae,1981,74:233-254.