史红毅,孙云鹏,欧阳晴,关成国,王伟,陈哲,周传明

• 1:中国科学院南京地质古生物研究所现代古生物学和地层学国家重点实验室
• 2:中国科学院大学
• 3:中国地质大学(武汉)生物地质与环境地质国家重点实验室
• 4:中国科学院大学南京学院

摘要(Abstract)：

作为新元古代全球冰期结束的标志,盖帽碳酸盐岩在全球广泛分布。盖帽碳酸盐岩特殊的沉积构造和地球化学特征使其长时间以来成为学界研究新元古代冰期事件的重点关注对象。湖北宜昌三斗坪地区埃迪卡拉系陡山沱组底部盖帽碳酸盐岩中具极负碳同位素值(δ~(13)C最低值小于-40‰,VPDB)方解石的形成与甲烷氧化有关,被认为是甲烷水合物释放导致冰期结束和盖帽碳酸盐岩沉积这一假说的关键证据。但也有学者认为这些具极负碳同位素值方解石是在盖帽碳酸盐岩沉积之后形成的,因此与冰期结束和盖帽碳酸盐岩沉积无关。为探讨盖帽碳酸盐岩中具极负碳同位素值方解石的形成时间,本文利用近年来发展迅速的碳酸盐矿物激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)U-Pb定年技术,分别对湖北宜昌九龙湾剖面陡山沱组底部盖帽碳酸盐岩裂隙和孔洞中的暗色方解石、白云石胶结物、白云石围岩进行了年龄测定。测试结果表明,暗色方解石的形成时间为593.7±8.7 Ma (2σ, n=111,MSWD=3.6),比盖帽白云岩沉积时间晚约40Myr,而白云石胶结物和围岩的分析测试获得了与方解石近似的U-Pb年龄,表明后期富甲烷流体的活动也对裂隙早期胶结物和周围的白云岩造成了影响。

关键词(KeyWords)： 盖帽碳酸盐岩;极负碳同位素值方解石;碳酸盐岩U-Pb定年;陡山沱组;宜昌

Abstract:

Keywords:

基金项目(Foundation): 中国科学院战略性先导科技专项(XDB26000000);; 国家自然科学基金(42192501、41921002);; 生物地质与环境地质国家重点实验室开放课题(GBL22106)共同资助

作者(Author): 史红毅,孙云鹏,欧阳晴,关成国,王伟,陈哲,周传明

DOI: 10.19839/j.cnki.dcxzz.2023.0005

参考文献(References)：

• 高伊雪,邱昆峰,于皓丞,侯照亮,魏瑜吉.2022.碳酸盐矿物激光原位U-Pb定年基本原理,分析方法与地学应用[J].岩石矿物学杂志,41(4):786-803.
• 沈安江,胡安平,程婷,梁峰,潘文庆,俸月星,赵建新.2019.激光原位U-Pb同位素定年技术及其在碳酸盐岩成岩-孔隙演化中的应用[J].石油勘探与开发,46(6):1062-1073.
• 赵自强,邢裕盛,马国干,陈忆元.1985.长江三峡地区生物地层学(1):震旦纪分册[M].北京:地质出版社.
• Bao H,Fairchild I J,Wynn P M,Sp?tl C.2009.Stretching the envelope of past surface environments:Neoproterozoic glacial lakes from Svalbard[J].Science,323(5910):119-122.
• Bao H,Lyons J R,Zhou C.2008.Triple oxygen isotope evidence for elevated CO2 levels after a Neoproterozoic Glaciation[J].Nature,453(7194):504-506.
• Bernasconi S M,Da?ron M,Bergmann K D,Bonifacie M,Meckler A N,Affek HP,Anderson N,Bajnai D,Barkan E,Beverly E,Blamart D,Burgener L,Calmels D,Chaduteau C,Clog M,Davidheiser-Kroll B,Davies A,Dux F,Eiler J,Elliott B,Fetrow A C,Fiebig J,Goldberg S,Hermoso M,Huntington K W,Hyland E,Ingalls M,Jaggi M,John C M,Jost A B,Katz S,Kelson J,Kluge T,Kocken I J,Laskar A,Leutert T J,Liang D,Lucarelli J,Mackey TJ,Mangenot X,Meinicke N,Modestou S E,Müller I A,Murray S,Neary A,Packard N,Passey B H,Pelletier E,Petersen S,Piasecki A,Schauer A,Snell K E,Swart P K,Tripati A,Upadhyay D,Vennemann T,Winkelstern I,Yarian D,Yoshida N,Zhang N,Ziegler M.2021.Intercarb:A community effort to improve interlaboratory standardization of the carbonate clumped isotope thermometer using carbonate standards[J].Geochemistry,Geophysics,Geosystems,22(5):e2020GC009588.
• Bernasconi S M,Hu B,Wacker U,Fiebig J,Breitenbach S F M,Rutz T.2013.Background effects on faraday collectors in gas-source mass spectrometry and implications for clumped isotope measurements[J].Rapid Communications in Mass Spectrometry,27(5):603-612.
• Bernasconi S M,Müller I A,Bergmann K D,Breitenbach S F M,Fernandez A,Hodell D A,Jaggi M,Meckler A N,Millan I,Ziegler M.2018.Reducing uncertainties in carbonate clumped isotope analysis through consistent carbonate-based standardization[J].Geochemistry,Geophysics,Geosystems,19(9):2895-2914.
• Bristow T F,Bonifacie M,Derkowski A,Eiler J M,Grotzinger J P.2011.Ahydrothermal origin for isotopically anomalous cap dolostone cements from South China[J].Nature,474(7349):68-71.
• Calver C R,Crowley J L,Wingate M T D,Evans D A D,Raub T D,Schmitz M D.2013.Globally synchronous Marinoan Deglaciation indicated by U-Pb geochronology of the Cottons Breccia,Tasmania,Australia[J].Geology,41(10):1127-1130.
• Chang B,Li C,Liu D,Foster I,Tripati A,Lloyd M K,Maradiaga I,Luo G,An Z,She Z,Xie S,Tong J,Huang J,Algeo T J,Lyons T W,Immenhauser A.2020.Massive formation of early diagenetic dolomite in the Ediacaran ocean:Constraints on the“Dolomite Problem”[J].Proceedings of the National Academy of Sciences,117(25):14005-14014.
• Condon D,Zhu M,Bowring S,Wang W,Yang A,Jin Y.2005.U-Pb ages from the Neoproterozoic Doushantuo Formation,China[J].Science,308(5718):95-98.
• Cui H,Orland I J,Denny A,Kitajima K,Fournelle J H,Baele J-M,Winter N J,Goderis S,Claeys P,Valley J W,2019.Ice or Fire?Constraining the Origin of Isotopically Anomalous Cap Carbonate Cements by SIMS[M].Geological Society of America Abstracts with Programs.Denver Co.:Geological Society of America.
• Dennis K J,Affek H P,Passey B H,Schrag D P,Eiler J M.2011.Defining an absolute reference frame for‘clumped’isotope studies of CO2[J].Geochimica et Cosmochimica Acta,75(22):7117-7131.
• Fiebig J,Bajnai D,L?ffler N,Methner K,Krsnik E,Mulch A,Hofmann S.2019.Combined high-precision?48 and?47 analysis of carbonates[J].Chemical Geology,522:186-191.
• Gan T,Luo T,Pang K,Zhou C,Zhou G,Wan B,Li G,Yi Q,Czaja A D,Xiao S.2021.Cryptic terrestrial fungus-like fossils of the early Ediacaran Period[J].Nature Communications,12(1):641.
• He R,Lang X,Shen B.2021.A rapid rise of seawater δ13C during the deglaciation of the Marinoan Snowball Earth[J].Global and Planetary Change,207:103672.
• Hoffman P F,Kaufman A J,Halverson G P,Schrag D P.1998.ANeoproterozoic Snowball Earth[J].Science,281(5381):1342-1346.
• Hoffman P F,Schrag D P.2002.The Snowball Earth hypothesis:Testing the limits of global change[J].Terra Nova,14(3):129-155.
• Jahn B,Cuvellier H.1994.Pb-Pb and U-Pb geochronology of carbonate rocks:An assessment[J].Chemical Geology,115(1):125-151.
• Jiang G,Kennedy M J,Christie-Blick N.2003.Stable isotopic evidence for methane seeps in Neoproterozoic postglacial cap carbonates[J].Nature,426(6968):822-826.
• Jiang G,Kennedy M J,Christie-Blick N,Wu H,Zhang S.2006a.Stratigraphy,sedimentary structures,and textures of the Late Neoproterozoic Doushantuo cap carbonate in South China[J].Journal of Sedimentary Research,76(7):978-995.
• Jiang G,Shi X,Zhang S.2006b.Methane seeps,methane hydrate destabilization,and the Late Neoproterozoic postglacial cap carbonates[J].Chinese Science Bulletin,51(10):1152-1173.
• Jiang G,Shi X,Zhang S,Wang Y,Xiao S.2011.Stratigraphy and paleogeography of the Ediacaran Doushantuo Formation (ca.635-551 Ma) in South China[J].Gondwana Research,19(4):831-849.
• Jiang L,Shen A,Wang Z,Hu A,Wang Y,Luo X,Liang F,Azmy K,Pan L.2022.U-Pb geochronology and clumped isotope thermometry study of Neoproterozoic dolomites from China[J].Sedimentology,69(7):2925-2945.
• John C M,Bowen D.2016.Community software for challenging isotope analysis:First applications of‘easotope’to clumped isotopes[J].Rapid Communications in Mass Spectrometry,30(21):2285-2300.
• Kennedy M J,Christie-Blick N,Sohl L E.2001.Are Proterozoic cap carbonates and isotopic excursions a record of gas hydrate destabilization following earth’s coldest intervals[J]?Geology,29(5):443-446.
• Lan Z,Roberts N M W,Zhou Y,Zhang S,Li Z,Zhao T.2022a.Application of in situ U-Pb carbonate geochronology to Stenian-Tonian Successions of North China[J].Precambrian Research,370:106551.
• Lan Z,Wu S,Roberts N M W,Zhang S,Cao R,Wang H,Yang Y.2022b.Geochronological and geochemical constraints on the origin of highly13Ccarb-depleted calcite in basal Ediacaran cap carbonate[J].Geological Magazine,159(8):1323-1334.
• Lan Z,Wu S,Wang F,Liu B,Shi K,Sun J,Cao R,Li X.2023.A ca.290 Ma hydrothermal calcite in Cambrian dolostone[J].Marine and Petroleum Geology,147:106011.
• Mc Fadden K A,Huang J,Chu X,Jiang G,Kaufman A J,Zhou C,Yuan X,Xiao S.2008.Pulsed oxidation and biological evolution in the Ediacaran Doushantuo Formation[J].Proceedings of the National Academy of Sciences,105(9):3197-3202.
• Moorbath S,Taylor P N,Orpen J L,Treloar P,Wilson J F.1987.First direct radiometric dating of Archaean stromatolitic limestone[J].Nature,326(6116):865-867.
• Müller I A,Fernandez A,Radke J,van Dijk J,Bowen D,Schwieters J,Bernasconi S M.2017.Carbonate clumped isotope analyses with the Long-Integration Dual-Inlet (LIDI) workflow:Scratching at the lower sample weight boundaries[J].Rapid Communications in Mass Spectrometry,31(12):1057-1066.
• Ouyang Q,Zhou C,Xiao S,Guan C,Chen Z,Yuan X,Sun Y.2021.Distribution of Ediacaran acanthomorphic acritarchs in the Lower Doushantuo Formation of the Yangtze Gorges Area,South China:Evolutionary and stratigraphic implications[J].Precambrian Research,353:106005.
• Passey B H,Henkes G A.2012.Carbonate clumped isotope bond reordering and geospeedometry[J].Earth and Planetary Science Letters,351-352:223-236.
• Peng Y,Bao H,Jiang G,Crockford P,Feng D,Xiao S,Kaufman A J,Wang J.2022.A transient peak in marine sulfate after the 635 Ma Snowball Earth[J].Proceedings of the National Academy of Sciences,119(19):e2117341119.
• Prave A R,Condon D J,Hoffmann K H,Tapster S,Fallick A E.2016.Duration and nature of the End-Cryogenian (Marinoan) glaciation[J].Geology,44(8):631-634.
• Rasbury E T,Cole J M.2009.Directly dating geologic events:U-Pb dating of carbonates[J].Reviews of Geophysics,47:1-27.
• Roberts N M W,Drost K,Horstwood M S A,Condon D J,Chew D,Drake H,Milodowski A E,Mc Lean N M,Smye A J,Walker R J,Haslam R,Hodson K,Imber J,Beaudoin N,Lee J K.2020.Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb carbonate geochronology:Strategies,progress,and limitations[J].Geochronology,2(1):33-61.
• Wang J,Jiang G,Xiao S,Li Q,Wei Q.2008.Carbon isotope evidence for widespread methane seeps in the ca.635 Ma Doushantuo Cap Carbonate in South China[J].Geology,36(5):347-350.
• Woodhead J,Petrus J A.2019.Exploring the advantages and limitations of in situ U-Pb carbonate geochronology using speleothems[J].Geochronology,1:69-84.
• Woodhead J,Pickering R.2012.Beyond 500 ka:Progress and prospects in the U-Pb chronology of speleothems,and their application to studies in palaeoclimate,human evolution,biodiversity and tectonics[J].Chemical Geology,322-323:290-299.
• Zhou C,Bao H,Peng Y,Yuan X.2010.Timing the deposition of 17O-depleted barite at the aftermath of Nantuo Glacial meltdown in South China[J].Geology,38(10):903-906.
• Zhou C,Guan C,Cui H,Ouyang Q,Wang W.2016.Methane-derived authigenic carbonate from the lower Doushantuo Formation of South China:Implications for seawater sulfate concentration and global carbon cycle in the early Ediacaran Ocean[J].Palaeogeography,Palaeoclimatology,Palaeoecology,461:145-155.
• Zhou C,Huyskens M H,Lang X,Xiao S,Yin Q Z.2019.Calibrating the terminations of cryogenian global glaciations[J].Geology,47(3):251-254.
• Zhou C,Xiao S.2007.Ediacaran δ13C chemostratigraphy of South China[J].Chemical Geology,237(1):89-108.
• Zhou G,Luo T,Zhou M,Xing L,Gan T.2017.A ubiquitous hydrothermal episode recorded in the sheet-crack cements of a Marinoan Cap Dolostone of South China:Implication for the origin of the extremely 13C-depleted calcite cement[J].Journal of Asian Earth Sciences,134:63-71.