REEs Geochemistry of Doushantuo Phosphorites and Modification during Post Sedimentary Stages in Weng'an Area, South China

XIE Qi lai; CHEN Duo fu; QI Liang; CHEN Xian pei

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Article Navigation > Acta Sedimentologica Sinica > 2003 > 21(4): 627-633

XIE Qi lai, CHEN Duo fu, QI Liang, CHEN Xian pei. REEs Geochemistry of Doushantuo Phosphorites and Modification during Post Sedimentary Stages in Weng'an Area, South China[J]. Acta Sedimentologica Sinica, 2003, 21(4): 627-633.

Citation:

XIE Qi lai, CHEN Duo fu, QI Liang, CHEN Xian pei. REEs Geochemistry of Doushantuo Phosphorites and Modification during Post Sedimentary Stages in Weng'an Area, South China[J]. Acta Sedimentologica Sinica, 2003, 21(4): 627-633.

REEs Geochemistry of Doushantuo Phosphorites and Modification during Post Sedimentary Stages in Weng'an Area, South China

1.
Basin & Reservoir Research Center, University of Petroleum, Beijing 102249;
2.
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640;
3.
Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002

Received Date: 2003-05-20
Publish Date: 2003-12-10

Abstract

The Neoproterozoic Doushantou phodphorites in Weng' an, South China, preserved a unique assemblage of a most likely the earliest metazoan in the world.The reconst ruction of paleoenvironmental change, when the Weng' an metazoan fauna emerged, is most important.But REE diagenetic modification of the Doushantou phosphorites must be evaluated.This paper is to discuss the REE modification in the Weng' an phosphorites during post sedimentary stages by REE geochemistry of phosphatic and dolomitic cements, phosphatic clasts in the upper phosphorites, phosphorite and shale bands in the lower phosphorites. The later diagenetic mineral phases:dolomitic and phosphatic cements display similar North American Shale normalized REE patterns with associated authigenic phosphatic phases and suggest that the REE geochemical characteristics in the Doushantuo phosphorites could be taken as primary signatures of paleoseawater conditions and may imply that the REE in the authigenic phosphatic phases were not modified during their burial, digenesis and surface weathering.The different REE characteristics in the phosphatic bands and associated shale bands in couplet samples suggested that the REE digenetic reaction might be only taken place within -strata but not between strata.Negative correlation of ErN/LuN and positive correlation of LaN/NdN with Ce/Ce^*suggests that the HREE and LREE depletions may derive from the change of paleoseawater redox condition, and HREE, LREE appear to be more depletion in the more oxidizing condition caused more Ce depletion.
- rare earth elements,
- modification in post sedimentary stages,
- Doushantuo phosphorites,
- terminal Proterozic,
- Weng' an

References

[1]	Piper D Z. Rare earth elements in the sedimentary cycle: a summary[J]. Chemical Geology, 1974, 14: 285～304
[2]	Fleet A J. Aqueous and sedimentary geochemistry of the rare earth elements[A]. In: Henderson P ed. Rare Earth Element Geochemisrty[C]. Amsterdam: Elsevier, 1984. 343～373
[3]	Wright J, Seymour R S, Shaw H F. REE and Nd isotopes in conodont apatite: variations with geological age and depositional environment[A]. In: Clark D L ed. Conodont Biofacies and Provinciales[C]. Geol Soc Am Spec Paper, 1984, 196: 325～340
[4]	Wright J, Schrader H, Holser W T. Paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite[J]. Geochimica et Cosmochimica Acta, 1987, 51: 637～644
[5]	Grandjean P, Cappetta H, Albarede F. The rare earth and (Nd of 40～70 Ma old fish debris from the West African platform[J]. Geophysica Research Letter, 1988,15:389～392
[6]	Grandjean P, Cappetta H, Michard A, et al. The assessment of REEs patterns and 143 Nd/144Nd ratios in fish remains[J]. Earth Planet Science Letter, 1987, 84:181～196
[7]	Bertram C J, Elderfield H, Aldridge R J, et al. 87 Sr/86Sr, 143 Nd/144Nd and REEs in Silurian phosphatic fossils[J]. Earth Planet Science Letter, 1992,113: 239～249
[8]	Jarvis I, Burnett W, Nathan Y, et al. Phosphorite geochemistry: state-of-the-art and environment concerns[J]. Eclogae Geol Helv, 1994,87: 643～700
[9]	Bellanca A, Masetti D, Neri R. Rare earth elements in limestone/marlstone couplets from the Albian-Cenomanian Cismon section (Venetioan region, northern Italy): assessing REE sensitivity to environmental changes[J]. Chemical Geology, 1997,41: 141～152
[10]	Ilyin A V. Rare-earth geochemistry of 'old' phosphorites and probability of syngenetic precipitation and accumulation of phosphate[J]. Chemical Geology,1998,144: 243～256
[11]	Yang J, Sun W, Wang Z, et al. Variations in Sr and C isotopes and Ce anomalies in successions from China: evidence for the oxygenation of Neoproterozoic seawater?[J] Precambrian Research, 1999,93: 215～233
[12]	Mazumdar A, Banerjee D M, Schidlowski M, et al. Rare-earth elements and stable isotope geochemistry of early Cambrian chert-phosphorite assemblages from the Lower Tal Formation of the Krol Belt (lesser Himalaya, India)[J]. Chemical Geology, 1999, 156: 275～297
[13]	Elderfield H, Pagett R. Rare Earth elements in Ichthyoliths: variations with redox conditions and depositional environment[A]. In: Riley J P ed. Science of the Total Environment[C]. Amsterdam: Elsevier, 1986. 175～197
[14]	Elderfield H, Sholkovitz E R. Rare earth elements in the pore waters of reducing nearshore sediments[J]. Earth Planet Science Letter, 1987,82: 280～288
[15]	German C R, Elderfield H. Application of the Ce anomaly as a paleoredox indicator: the ground rules[J]. Paleoceanography, 1990,5: 823～833
[16]	Murray R W, Buchholtz M R, Gerlach D C, et al. Rare earth, major, and trace element composition of Monterey and DSDP chert and associated host sediments: assessing the influence of chemical fractionation during diagenesis[J]. Geochimica et Cosmochimica Acta, 1992,56: 2 657～2 671
[17]	Reynard B, Lecuyer C, Grandjean P. Crystal-chemical controls on rare-earth element concentrations in fossil biogenic apatites and implications for paleoenvironmental reconstructions[J]. Chemical Geology, 1999,155: 233～241
[18]	Shields G, Stille, P. Diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies: an isotopic and REE study of Cambrian phosphorites[J]. Chemical Geology, 2001, 175:29～48
[19]	McArthur J M, Walsh J N. Rare-earth geochemistry of phosphorites[J]. Chemical Geology, 1984, 47:191～220
[20]	Bonnoit-Courtois C, Flicoteaux R. Distribution of rare-earth and some trace elements in Tertiary phophorites from the Senegal Basin and their weathering products[J]. Chemical Geology, 1989, 75: 311～328
[21]	Hannigan R E, Sholkovitz E R. The development of middle rare earth element enrichments in freshwaters: weathering of phosphatic minerals[J]. Chemical Geology, 2001,175:495～508
[22]	Bertrand-Sarfati J, Flicoteaux R, Moussine-Pouchkine A, et al. Lower Cambrian apatitic stromatolites and phosphorites related to the glacio-eustatic cratonic rebound (Sahara, Algeria)[J]. Journal of Sedimentaary Research, 1997, 67: 957～974
[23]	Tricca A, Stille P, Steinmann M, et al. Rare earth elements and Sr and Nd isotopic compositions of dissolved and suspended loads from small river systems in the Vosges mountains (France), the river Rhine and groundwater[J]. Chemical Geology, 1999, 160: 139～158
[24]	Picard S, Lecuyer C, Barrat J, et al. Rare earth element contents of Jurassic fish and reptile teeth and their potential relation to seawater composition (Anglo-Paris Basin, France and England)[J]. Chemical Geology, 2002, 186: 1～16
[25]	安德鲁.诺尔, 肖书海. 论陡山沱组的年代[J]. 古生物学报, 1999,16(3):225～236 [Knoll, A. H., Xiao, S. H., 1999. On the age of the Doushantuo Formation[J]. Acta Micropalaeontologica Sinica, 1999, 16, 225～236]
[26]	薛耀松,唐天福,俞丛流. 贵州晚震旦世陡山沱组具骨骼动物化石的发现及地质意义[J].古生物学报,1992, 31(5): 530～539[Xue Y, Tang T, Yu C. Discovery of oldest skeletal fossils from Upper Sinian Doushantuo Formation in Weng'an, Guizhou and its significance[J]. Acta Palaeontologica Sinica, 1992,31(5): 530～539]
[27]	Yin L M, Xue Y S. An extraordinary microfossil assemblage from terminal Proterozoic phosphate deposits in South China[J]. Chinese Journal Botany, 1993,5:168～175
[28]	Li C W, Chen J Y, Hua T E. Precambrian Sponges with Cellular Structures[J]. Science, 1998, 279: 879～882
[29]	Xiao S H, Zhang Y, Knoll A H. Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite[J]. Nature, 1998, 391,553～558
[30]	Xiao S H, Yuan X L, Knoll A H. Eumetazoan fossils in terminal Proterozoic phosphorites?[J] Proc Natl Acad Sci USA, 2000a, 97: 13 684～13 689
[31]	Zhang Y, Yuan X L, Yin L M. Interpreting late Precambrian microfossils[J]. Science, 1998,282: 1783
[32]	Chen J Y, Oliveri P, Li C W, et al. Precambrian animal diversity: Putative phosphatized embryos from the Doushantuo Formation of China[J]. Proc Natl Acad Sci USA, 2000,97: 4 457～4 462
[33]	Yin C, Gao L. The microfossils in phosphate deposit in Doushantuo Sinian System, Weng'an, Guizhou Province[J]. Chinese Science Bulletin, 2000, 45: 279～284
[34]	Barfod G H, Albarede F, Knoll A H, et al. New Lu-Hf and Pb-Pb age onstraints on the earliest animal fossils[J]. Earth Planet Science Letter, 2002, 201: 203～212
[35]	Taylor S R, McLennan S M. The continental crust: Its composition and evolution[M]. Boston: Blackwell, 1985.1～312
[36]	王中刚,于学元,赵振华.稀土元素地球化学[M].北京:科学出版社, 1989. 247～278[Wang Zhonggang, Yu Xueyuan, Zhao Zhenhua. Rare earth element geochemistry[M]. Beijing: Science Press, 1989. 247～278]
[37]	Lecuyer C, Grandjean P, Barrat J, et al. 18 O and REE contents of phosphatic brachiopods: A comparison between modern and lower Paleozoic populations[J]. Geochimica et Cosmochimica Acta, 1998, 62:2 429～2 436
[38]	叶连俊.生物有机质成矿作用和成矿背景[M]. 北京: 科学出版社,1998. 1～462[Ye L J. Biomineralization and its geologic background[M]. Beijing: Science Press, 1998.1～462]

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通讯作者: 陈斌, bchen63@163.com

1.
沈阳化工大学材料科学与工程学院沈阳 110142

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REEs Geochemistry of Doushantuo Phosphorites and Modification during Post Sedimentary Stages in Weng'an Area, South China

1. Basin & Reservoir Research Center, University of Petroleum, Beijing 102249;

2. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640;

3. Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002

Received Date: 2003-05-20

Publish Date: 2003-12-10

Key words:

rare earth elements /
modification in post sedimentary stages /
Doushantuo phosphorites /
terminal Proterozic /
Weng' an

Abstract: The Neoproterozoic Doushantou phodphorites in Weng' an, South China, preserved a unique assemblage of a most likely the earliest metazoan in the world.The reconst ruction of paleoenvironmental change, when the Weng' an metazoan fauna emerged, is most important.But REE diagenetic modification of the Doushantou phosphorites must be evaluated.This paper is to discuss the REE modification in the Weng' an phosphorites during post sedimentary stages by REE geochemistry of phosphatic and dolomitic cements, phosphatic clasts in the upper phosphorites, phosphorite and shale bands in the lower phosphorites. The later diagenetic mineral phases:dolomitic and phosphatic cements display similar North American Shale normalized REE patterns with associated authigenic phosphatic phases and suggest that the REE geochemical characteristics in the Doushantuo phosphorites could be taken as primary signatures of paleoseawater conditions and may imply that the REE in the authigenic phosphatic phases were not modified during their burial, digenesis and surface weathering.The different REE characteristics in the phosphatic bands and associated shale bands in couplet samples suggested that the REE digenetic reaction might be only taken place within -strata but not between strata.Negative correlation of ErN/LuN and positive correlation of LaN/NdN with Ce/Ce^*suggests that the HREE and LREE depletions may derive from the change of paleoseawater redox condition, and HREE, LREE appear to be more depletion in the more oxidizing condition caused more Ce depletion.

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Reference (38)

[1]	Piper D Z. Rare earth elements in the sedimentary cycle: a summary[J]. Chemical Geology, 1974, 14: 285～304
[2]	Fleet A J. Aqueous and sedimentary geochemistry of the rare earth elements[A]. In: Henderson P ed. Rare Earth Element Geochemisrty[C]. Amsterdam: Elsevier, 1984. 343～373
[3]	Wright J, Seymour R S, Shaw H F. REE and Nd isotopes in conodont apatite: variations with geological age and depositional environment[A]. In: Clark D L ed. Conodont Biofacies and Provinciales[C]. Geol Soc Am Spec Paper, 1984, 196: 325～340
[4]	Wright J, Schrader H, Holser W T. Paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite[J]. Geochimica et Cosmochimica Acta, 1987, 51: 637～644
[5]	Grandjean P, Cappetta H, Albarede F. The rare earth and (Nd of 40～70 Ma old fish debris from the West African platform[J]. Geophysica Research Letter, 1988,15:389～392
[6]	Grandjean P, Cappetta H, Michard A, et al. The assessment of REEs patterns and 143 Nd/144Nd ratios in fish remains[J]. Earth Planet Science Letter, 1987, 84:181～196
[7]	Bertram C J, Elderfield H, Aldridge R J, et al. 87 Sr/86Sr, 143 Nd/144Nd and REEs in Silurian phosphatic fossils[J]. Earth Planet Science Letter, 1992,113: 239～249
[8]	Jarvis I, Burnett W, Nathan Y, et al. Phosphorite geochemistry: state-of-the-art and environment concerns[J]. Eclogae Geol Helv, 1994,87: 643～700
[9]	Bellanca A, Masetti D, Neri R. Rare earth elements in limestone/marlstone couplets from the Albian-Cenomanian Cismon section (Venetioan region, northern Italy): assessing REE sensitivity to environmental changes[J]. Chemical Geology, 1997,41: 141～152
[10]	Ilyin A V. Rare-earth geochemistry of 'old' phosphorites and probability of syngenetic precipitation and accumulation of phosphate[J]. Chemical Geology,1998,144: 243～256
[11]	Yang J, Sun W, Wang Z, et al. Variations in Sr and C isotopes and Ce anomalies in successions from China: evidence for the oxygenation of Neoproterozoic seawater?[J] Precambrian Research, 1999,93: 215～233
[12]	Mazumdar A, Banerjee D M, Schidlowski M, et al. Rare-earth elements and stable isotope geochemistry of early Cambrian chert-phosphorite assemblages from the Lower Tal Formation of the Krol Belt (lesser Himalaya, India)[J]. Chemical Geology, 1999, 156: 275～297
[13]	Elderfield H, Pagett R. Rare Earth elements in Ichthyoliths: variations with redox conditions and depositional environment[A]. In: Riley J P ed. Science of the Total Environment[C]. Amsterdam: Elsevier, 1986. 175～197
[14]	Elderfield H, Sholkovitz E R. Rare earth elements in the pore waters of reducing nearshore sediments[J]. Earth Planet Science Letter, 1987,82: 280～288
[15]	German C R, Elderfield H. Application of the Ce anomaly as a paleoredox indicator: the ground rules[J]. Paleoceanography, 1990,5: 823～833
[16]	Murray R W, Buchholtz M R, Gerlach D C, et al. Rare earth, major, and trace element composition of Monterey and DSDP chert and associated host sediments: assessing the influence of chemical fractionation during diagenesis[J]. Geochimica et Cosmochimica Acta, 1992,56: 2 657～2 671
[17]	Reynard B, Lecuyer C, Grandjean P. Crystal-chemical controls on rare-earth element concentrations in fossil biogenic apatites and implications for paleoenvironmental reconstructions[J]. Chemical Geology, 1999,155: 233～241
[18]	Shields G, Stille, P. Diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies: an isotopic and REE study of Cambrian phosphorites[J]. Chemical Geology, 2001, 175:29～48
[19]	McArthur J M, Walsh J N. Rare-earth geochemistry of phosphorites[J]. Chemical Geology, 1984, 47:191～220
[20]	Bonnoit-Courtois C, Flicoteaux R. Distribution of rare-earth and some trace elements in Tertiary phophorites from the Senegal Basin and their weathering products[J]. Chemical Geology, 1989, 75: 311～328
[21]	Hannigan R E, Sholkovitz E R. The development of middle rare earth element enrichments in freshwaters: weathering of phosphatic minerals[J]. Chemical Geology, 2001,175:495～508
[22]	Bertrand-Sarfati J, Flicoteaux R, Moussine-Pouchkine A, et al. Lower Cambrian apatitic stromatolites and phosphorites related to the glacio-eustatic cratonic rebound (Sahara, Algeria)[J]. Journal of Sedimentaary Research, 1997, 67: 957～974
[23]	Tricca A, Stille P, Steinmann M, et al. Rare earth elements and Sr and Nd isotopic compositions of dissolved and suspended loads from small river systems in the Vosges mountains (France), the river Rhine and groundwater[J]. Chemical Geology, 1999, 160: 139～158
[24]	Picard S, Lecuyer C, Barrat J, et al. Rare earth element contents of Jurassic fish and reptile teeth and their potential relation to seawater composition (Anglo-Paris Basin, France and England)[J]. Chemical Geology, 2002, 186: 1～16
[25]	安德鲁.诺尔, 肖书海. 论陡山沱组的年代[J]. 古生物学报, 1999,16(3):225～236 [Knoll, A. H., Xiao, S. H., 1999. On the age of the Doushantuo Formation[J]. Acta Micropalaeontologica Sinica, 1999, 16, 225～236]
[26]	薛耀松,唐天福,俞丛流. 贵州晚震旦世陡山沱组具骨骼动物化石的发现及地质意义[J].古生物学报,1992, 31(5): 530～539[Xue Y, Tang T, Yu C. Discovery of oldest skeletal fossils from Upper Sinian Doushantuo Formation in Weng'an, Guizhou and its significance[J]. Acta Palaeontologica Sinica, 1992,31(5): 530～539]
[27]	Yin L M, Xue Y S. An extraordinary microfossil assemblage from terminal Proterozoic phosphate deposits in South China[J]. Chinese Journal Botany, 1993,5:168～175
[28]	Li C W, Chen J Y, Hua T E. Precambrian Sponges with Cellular Structures[J]. Science, 1998, 279: 879～882
[29]	Xiao S H, Zhang Y, Knoll A H. Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite[J]. Nature, 1998, 391,553～558
[30]	Xiao S H, Yuan X L, Knoll A H. Eumetazoan fossils in terminal Proterozoic phosphorites?[J] Proc Natl Acad Sci USA, 2000a, 97: 13 684～13 689
[31]	Zhang Y, Yuan X L, Yin L M. Interpreting late Precambrian microfossils[J]. Science, 1998,282: 1783
[32]	Chen J Y, Oliveri P, Li C W, et al. Precambrian animal diversity: Putative phosphatized embryos from the Doushantuo Formation of China[J]. Proc Natl Acad Sci USA, 2000,97: 4 457～4 462
[33]	Yin C, Gao L. The microfossils in phosphate deposit in Doushantuo Sinian System, Weng'an, Guizhou Province[J]. Chinese Science Bulletin, 2000, 45: 279～284
[34]	Barfod G H, Albarede F, Knoll A H, et al. New Lu-Hf and Pb-Pb age onstraints on the earliest animal fossils[J]. Earth Planet Science Letter, 2002, 201: 203～212
[35]	Taylor S R, McLennan S M. The continental crust: Its composition and evolution[M]. Boston: Blackwell, 1985.1～312
[36]	王中刚,于学元,赵振华.稀土元素地球化学[M].北京:科学出版社, 1989. 247～278[Wang Zhonggang, Yu Xueyuan, Zhao Zhenhua. Rare earth element geochemistry[M]. Beijing: Science Press, 1989. 247～278]
[37]	Lecuyer C, Grandjean P, Barrat J, et al. 18 O and REE contents of phosphatic brachiopods: A comparison between modern and lower Paleozoic populations[J]. Geochimica et Cosmochimica Acta, 1998, 62:2 429～2 436
[38]	叶连俊.生物有机质成矿作用和成矿背景[M]. 北京: 科学出版社,1998. 1～462[Ye L J. Biomineralization and its geologic background[M]. Beijing: Science Press, 1998.1～462]

REEs Geochemistry of Doushantuo Phosphorites and Modification during Post Sedimentary Stages in Weng'an Area, South China

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