茂名油页岩沉积有机质特征及古气候意义
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摘要
基于海洋沉积确定的始新世晚期至渐新世早期(约33.5 Ma)的气候过渡期是新生代全球性气候事件,但长期以来相关的陆相沉积记录研究则比较缺乏。本文对形成于始新世晚期至渐新世早期的茂名油柑窝组油页岩样品进行了有机质丰度、烃类组成、单体烃碳同位素组成等分析,以期研究低纬度陆相沉积有机质对古近纪始新世—渐新世气候过渡期(EOT)的响应。研究结果显示,埋藏较浅的上部层位样品正构烷烃碳同位素组成显著正偏,为-19.1‰~-25.9‰,平均值为-22.2‰;而下部层位样品正构烷烃碳同位素组成在-23.7‰~-30.2‰,平均值为-26.3‰。两个样品正构烷烃碳同位素组成之差在1.5‰~8.1‰,平均值之差为4.6‰。正构烷烃碳同位素组成的显著差异指示了EOT低纬度陆相古气候变化引起的陆相有机质响应,而这种响应与当时大气CO_2浓度和海洋温度降低导致的气候和植物群落变化密切相关,即可能存在着C_3植物向C_4植物的转化、C_4植物的迅速增加并最终导致沉积有机质碳同位素组成的变化;也可能是由于大气CO_2浓度降低导致的大气CO_2碳同位素组成整体正偏的结果。很显然,进一步详细的连续剖面分析将对研究古近纪EOT低纬度陆相古气候变化提供重要科学依据。
The late Eocene to the early Oligocene(about 33.5Ma)climate transition determined by the marine sediment studies was a global event based on marine sediments during the Paleogene,while there is few researches on the terrestrial sediment records of this climate transition.The Youganwo Formation oil shales from Maoming basin of Guangdong Province,deposited during the late Eocene to the early Oligocene,have been studied in terms of organic matter abundance,hydrocarbon components and the carbon isotopic composition of individual hydrocarbon compounds,and aiming to study the response of terrestrial organic matter to the Eocene-Oligocene transition(EOT)at the low latitude region.The results show that theδ~(13)C composition of n-alkanes in the shallower buried sample display a significant positive excursion ranged from-19.1‰ and-25.9‰ with an average of-22.2‰.By contrast,theδ~(13)C composition of n-alkanes in the deeper buried sample is much negative and varied from-23.7‰ and-30.2‰ with averaged at-26.3‰.The difference between the δ~(13)C compositions of corresponding n-alkanes in these two samples vary from 1.5‰to 8.1‰ with an average deviation of 4.6‰.This significant shift in theδ~(13)C composition of n-alkanes signals that the terrestrial organism(s)at the low latitude land response to the paleoclimate changes which may closely related to the decrease in the concentration of atmospheric CO_2 and the ocean temperature during EOT.Therefore,the discrepancy in theδ~(13)C composition of n-alkanes may suggest that there was an significant shift or increase from C_3 plant to C_4 plant at the low altitude continental region of Maoming basin,which resulted in a remarkable change in theδ~(13)C composition of sedimentary organic matter;while it is also possible that the positive excursion of organic matter might be due to the decrease in the concentration of atmospheric CO_2 that gives rise to theδ~(13)C composition of atmospheric CO_2.Finally,this primary study suggests that more detailed research on the Maoming oil shale could provide some critical information to a better understanding of low latitude continental paleoclimate changes during EOT.
The late Eocene to the early Oligocene(about 33.5Ma)climate transition determined by the marine sediment studies was a global event based on marine sediments during the Paleogene,while there is few researches on the terrestrial sediment records of this climate transition.The Youganwo Formation oil shales from Maoming basin of Guangdong Province,deposited during the late Eocene to the early Oligocene,have been studied in terms of organic matter abundance,hydrocarbon components and the carbon isotopic composition of individual hydrocarbon compounds,and aiming to study the response of terrestrial organic matter to the Eocene-Oligocene transition(EOT)at the low latitude region.The results show that theδ~(13)C composition of n-alkanes in the shallower buried sample display a significant positive excursion ranged from-19.1‰ and-25.9‰ with an average of-22.2‰.By contrast,theδ~(13)C composition of n-alkanes in the deeper buried sample is much negative and varied from-23.7‰ and-30.2‰ with averaged at-26.3‰.The difference between the δ~(13)C compositions of corresponding n-alkanes in these two samples vary from 1.5‰to 8.1‰ with an average deviation of 4.6‰.This significant shift in theδ~(13)C composition of n-alkanes signals that the terrestrial organism(s)at the low latitude land response to the paleoclimate changes which may closely related to the decrease in the concentration of atmospheric CO_2 and the ocean temperature during EOT.Therefore,the discrepancy in theδ~(13)C composition of n-alkanes may suggest that there was an significant shift or increase from C_3 plant to C_4 plant at the low altitude continental region of Maoming basin,which resulted in a remarkable change in theδ~(13)C composition of sedimentary organic matter;while it is also possible that the positive excursion of organic matter might be due to the decrease in the concentration of atmospheric CO_2 that gives rise to theδ~(13)C composition of atmospheric CO_2.Finally,this primary study suggests that more detailed research on the Maoming oil shale could provide some critical information to a better understanding of low latitude continental paleoclimate changes during EOT.
引文
[1]Coxall H K,Wilson P A,Plike H,et al.Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean[J].Nature,2005,433:53-57.
[2]Kennett J P.Cenozoic evolution of Antarctic glaciation,the circum-Antarctic Ocean,and their impact on global paleoceanography[J].Journal of Geophysical Research,1977,82(27):3843-3860.
[3]Pearson P N,Foster G L,Wade B S.Atmospheric carbon dioxide through the Eocene-Oligocene climate transition[J].Nature,2009,461:1110-1113.
[4]Coxall H K,Pearson P N.The Eocene-Oligocene transition[M]∥Williams M,et al.Deep-Time Perspectives on Climate Change:Marrying the Signal from Computer Models and Biological Proxies.London:The Micropalaeontological Society,Special Publications,2007:357-387.
[5]Stephen T G,Hooker J J,Collinson M E,et al.Summer temperatures of Late Eocene to Early Oligocene freshwaters[J].Geology,2005,33(3):189-192.
[6]Kohn M J,Josef J A,Madden R,et al.Climate stability across the Eocene-Oligocene transition,southern Argentina[J].Geology,2004,32(7):621-624.
[7]Liu Z H,Pagani M,Zinniker D,et al.Global cooling during the Eocene-Oligocene climate transition[J].Science,2009,323:1187-1190.
[8]Hren M T,Sheldon N D,Grimes S T,et al.Terrestrial cooling in Northern Europe during the Eocene-Oligocene transition[J].PNAS,2013,110(19):7562-7567.
[9]Eldrett J S,Greenwood D R,Harding I C,et al.Increased seasonality through the Eocene to Oligocene transition in northern high latitudes[J].Nature,2009,459:969-973.
[10]Dupont-Nivet G,Krijgsman W,Langereis C G,et al.Tibetan plateau aridification linked to global cooling at the EoceneOligocene transition[J].Nature,2007,445:635-638.
[11]Meng J,McKenna M.Faunal turnovers of Palaeogene mammals from the Mongolian Plateau[J].Nature,1998,394:364-367.
[12]宋博文.柴达木盆地北缘早始新世—上新世环境演变及生物群研究[D].武汉:中国地质大学(武汉),2013.
[13]南颐,周国强.广东省岩石地层[M].武汉:中国地质大学出版社,1996:177-178.
[14]严焕榕,朱建伟,李殿超,等.茂名盆地金塘矿区油页岩特征及形成条件[J].世界地质,2006,25(4):407-410.
[15]金建华.广东茂名盆地油柑窝组的地质时代[J].地质学杂志,2008,32(1):47-50.
[16]傅家谟,徐芬芳,陈德玉,等.茂名油页岩中生物输入的标志化合物[J].地球化学,1985(2):99-113.
[17]Brassell S C,Eglinton G,Fu J M.Biological marker compounds as indicators of the depositional history of the Maoming oil shale[J].Organic Geochemistry,1986,10(4/5/6):927-941.
[18]于志强,彭平安,盛国英,等.茂名与江汉第三系油页岩中生物标志物碳同位素研究[J].科学通报,2000,45:2783-2788.
[19]郭敏,周明文,李瑞,等.广东茂名盆地油页岩成矿因素分析[J].华南地产与矿产,2009,2:47-51.
[20]李殿超,朱建伟,严焕榕,等.广东省茂名盆地油页岩的沉积特征及分布规律[J].吉林大学学报,2006,36(6):938-943.
[21]贾国东,彭平安.有机生物地球化学与晚新生代古全球变化研究[J].地学前缘,2005,12(2):179-187.
[22]Collister J W,Rieley G,Stern B,et al.Compound-specificδ13C analyses of leaf lipids from plants with differing carbon dioxide metabolisms[J].Organic Geochemistry,1994,21(6/7):619-627.
[23]Grice K,Schouten S,Peters K E,et al.Molecular isotopic characterisation of hydrocarbon biomarkers in Palaeocene-Eocene evaporitic,lacustrine source rocks from the Jianghan Basin,China[J].Organic Geochemistry,1998,29(5/6/7):1745-1764.
[24]Games,L M,Hayes-Robert J M,Gunsalus P.Methane-producing bacteria:Natural fractionations of the stable carbon isotopes[J].Geochimica et Cosmochimica Acta,1978,42(8):1295-1297.
[25]Whiticar,M J,Faber E,Schoell M.Biogenic methane formation in marine and fresh-water environments:CO2reduction vs.acetate fermentation-isotope evidence[J].Geochimica et Cosmochimica Acta,1986,50(5):693-709.
[26]Hussler G,Albrecht P,Ourisson G.Benzohopanes,a novel family of hexacyclic geomarkers in sediments and petroleums[J].Tetrahedron Letters,1984,25(11):1179-1182.
[27]盛国英,傅家谟,周中毅,等.检出于侏罗系沉积岩的一类新标志化合物:苯并藿烷[J].地球化学,1985(1):75-79.
[28]Ourisson G,Albrecht P,Rohmer M.Predictive microbial biochemistry:From molecular fossils to prokaryotic membranes[J].Trend in Biochemical Sciences,1982,7(7):236-239.
[29]Zachos J C,Quinn T M,Salamy K A.High-resolution(104years)deep-sea foraminiferal stable isotope records of the Eocene-Oligocene climate transition[J].Paleoceanography,1996,11(3):251-266.
[30]刘志飞,拓守廷,赵泉鸿,等.南大西洋深水渐新世初大冰期事件[J].科学通报,2004,49(17):1793-1800.
[31]Pearson P N,McMillan I K,Wade B S,et al.Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania[J].Geology,2008,36(2):179-182.
[32]Pusz A E,Thunell R C,Miller K G.Deep water temperature,carbonate ion,and ice volume changes across the Eocene-Oligocene climate transition[J].Paleoceanography,2011,26:PA2005.
[33]韩家懋,王国安,刘东生.C4植物的出现与全球环境变化[J].地学前缘,2002,9(1):233-243
[34]Pagani M,Zachos J C,Freeman K H,et al.Marked decline in atmospheric carbon dioxide concentrations during the Paleogene[J].Science,2005,309:600-603.
[35]Huber M,Nof D.The ocean circulation in the southern hemisphere and its climatic impacts in the Eocene[J].Palaeogeography,Palaeoclimatology,Palaeoecology,2006,231(1/2):9-28.
[36]Sunmons R E,Powell T G.Chlorobiaceae in Palaeozoic sea revealed by biological markers isotopes and geology[J].Nature,1986,319:763-765.
[37]李振西,范璞,李景贵,等.芳基类异戊二烯生标在指相上的应用[J].沉积学报,1998,16(2):9-13.
[38]冯子辉,方伟,李振广,等.松辽盆地陆相大规模优质烃源岩沉积环境的地球化学标志[J].中国科学:地球科学,2011,41(9):1235-1267.
[39]Sinninghe-DamstéJ S,Keely B J,Betts S E,et al.Variations in abundances and distributions of isoprenoid chromans and long-chain alkylbenzenes in sediments of the Mulhouse Basin:A molecular sedimentary record of palaeosalinity[J].Organic Geochemistry,1993,20(8):1201-1215.
[40]Schwark L,Vliex M,Schaeffer P.Geochemical characterization of Malm Zeta laminated carbonates from the Franconian Alb,SW-Germany(II)[J].Organic Geochemistry,1998,29(8):1921-1952.
[41]Bechtel A,Gawlick H J,Gratzer R,et al.Molecular indicators of palaeosalinity and depositional environment of small scale basins within carbonate platforms:The late Triassic Hauptdolomite Wiestalstausee section near Hallein[J].Organic Geochemistry,2007,38(1):92-111.
[42]王丽,宋之光.松辽盆地嫩江组脱羟基维生素E的分布及其地球化学意义[J].地球化学,2010,39(5):469-478.
[43]卢鸿,孙永革,彭平安.轮南油田原油中三甲基苯基类异戊二烯化合物的检出及其意义[J].高校地质学报,2007,10(2):283-289.
[2]Kennett J P.Cenozoic evolution of Antarctic glaciation,the circum-Antarctic Ocean,and their impact on global paleoceanography[J].Journal of Geophysical Research,1977,82(27):3843-3860.
[3]Pearson P N,Foster G L,Wade B S.Atmospheric carbon dioxide through the Eocene-Oligocene climate transition[J].Nature,2009,461:1110-1113.
[4]Coxall H K,Pearson P N.The Eocene-Oligocene transition[M]∥Williams M,et al.Deep-Time Perspectives on Climate Change:Marrying the Signal from Computer Models and Biological Proxies.London:The Micropalaeontological Society,Special Publications,2007:357-387.
[5]Stephen T G,Hooker J J,Collinson M E,et al.Summer temperatures of Late Eocene to Early Oligocene freshwaters[J].Geology,2005,33(3):189-192.
[6]Kohn M J,Josef J A,Madden R,et al.Climate stability across the Eocene-Oligocene transition,southern Argentina[J].Geology,2004,32(7):621-624.
[7]Liu Z H,Pagani M,Zinniker D,et al.Global cooling during the Eocene-Oligocene climate transition[J].Science,2009,323:1187-1190.
[8]Hren M T,Sheldon N D,Grimes S T,et al.Terrestrial cooling in Northern Europe during the Eocene-Oligocene transition[J].PNAS,2013,110(19):7562-7567.
[9]Eldrett J S,Greenwood D R,Harding I C,et al.Increased seasonality through the Eocene to Oligocene transition in northern high latitudes[J].Nature,2009,459:969-973.
[10]Dupont-Nivet G,Krijgsman W,Langereis C G,et al.Tibetan plateau aridification linked to global cooling at the EoceneOligocene transition[J].Nature,2007,445:635-638.
[11]Meng J,McKenna M.Faunal turnovers of Palaeogene mammals from the Mongolian Plateau[J].Nature,1998,394:364-367.
[12]宋博文.柴达木盆地北缘早始新世—上新世环境演变及生物群研究[D].武汉:中国地质大学(武汉),2013.
[13]南颐,周国强.广东省岩石地层[M].武汉:中国地质大学出版社,1996:177-178.
[14]严焕榕,朱建伟,李殿超,等.茂名盆地金塘矿区油页岩特征及形成条件[J].世界地质,2006,25(4):407-410.
[15]金建华.广东茂名盆地油柑窝组的地质时代[J].地质学杂志,2008,32(1):47-50.
[16]傅家谟,徐芬芳,陈德玉,等.茂名油页岩中生物输入的标志化合物[J].地球化学,1985(2):99-113.
[17]Brassell S C,Eglinton G,Fu J M.Biological marker compounds as indicators of the depositional history of the Maoming oil shale[J].Organic Geochemistry,1986,10(4/5/6):927-941.
[18]于志强,彭平安,盛国英,等.茂名与江汉第三系油页岩中生物标志物碳同位素研究[J].科学通报,2000,45:2783-2788.
[19]郭敏,周明文,李瑞,等.广东茂名盆地油页岩成矿因素分析[J].华南地产与矿产,2009,2:47-51.
[20]李殿超,朱建伟,严焕榕,等.广东省茂名盆地油页岩的沉积特征及分布规律[J].吉林大学学报,2006,36(6):938-943.
[21]贾国东,彭平安.有机生物地球化学与晚新生代古全球变化研究[J].地学前缘,2005,12(2):179-187.
[22]Collister J W,Rieley G,Stern B,et al.Compound-specificδ13C analyses of leaf lipids from plants with differing carbon dioxide metabolisms[J].Organic Geochemistry,1994,21(6/7):619-627.
[23]Grice K,Schouten S,Peters K E,et al.Molecular isotopic characterisation of hydrocarbon biomarkers in Palaeocene-Eocene evaporitic,lacustrine source rocks from the Jianghan Basin,China[J].Organic Geochemistry,1998,29(5/6/7):1745-1764.
[24]Games,L M,Hayes-Robert J M,Gunsalus P.Methane-producing bacteria:Natural fractionations of the stable carbon isotopes[J].Geochimica et Cosmochimica Acta,1978,42(8):1295-1297.
[25]Whiticar,M J,Faber E,Schoell M.Biogenic methane formation in marine and fresh-water environments:CO2reduction vs.acetate fermentation-isotope evidence[J].Geochimica et Cosmochimica Acta,1986,50(5):693-709.
[26]Hussler G,Albrecht P,Ourisson G.Benzohopanes,a novel family of hexacyclic geomarkers in sediments and petroleums[J].Tetrahedron Letters,1984,25(11):1179-1182.
[27]盛国英,傅家谟,周中毅,等.检出于侏罗系沉积岩的一类新标志化合物:苯并藿烷[J].地球化学,1985(1):75-79.
[28]Ourisson G,Albrecht P,Rohmer M.Predictive microbial biochemistry:From molecular fossils to prokaryotic membranes[J].Trend in Biochemical Sciences,1982,7(7):236-239.
[29]Zachos J C,Quinn T M,Salamy K A.High-resolution(104years)deep-sea foraminiferal stable isotope records of the Eocene-Oligocene climate transition[J].Paleoceanography,1996,11(3):251-266.
[30]刘志飞,拓守廷,赵泉鸿,等.南大西洋深水渐新世初大冰期事件[J].科学通报,2004,49(17):1793-1800.
[31]Pearson P N,McMillan I K,Wade B S,et al.Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania[J].Geology,2008,36(2):179-182.
[32]Pusz A E,Thunell R C,Miller K G.Deep water temperature,carbonate ion,and ice volume changes across the Eocene-Oligocene climate transition[J].Paleoceanography,2011,26:PA2005.
[33]韩家懋,王国安,刘东生.C4植物的出现与全球环境变化[J].地学前缘,2002,9(1):233-243
[34]Pagani M,Zachos J C,Freeman K H,et al.Marked decline in atmospheric carbon dioxide concentrations during the Paleogene[J].Science,2005,309:600-603.
[35]Huber M,Nof D.The ocean circulation in the southern hemisphere and its climatic impacts in the Eocene[J].Palaeogeography,Palaeoclimatology,Palaeoecology,2006,231(1/2):9-28.
[36]Sunmons R E,Powell T G.Chlorobiaceae in Palaeozoic sea revealed by biological markers isotopes and geology[J].Nature,1986,319:763-765.
[37]李振西,范璞,李景贵,等.芳基类异戊二烯生标在指相上的应用[J].沉积学报,1998,16(2):9-13.
[38]冯子辉,方伟,李振广,等.松辽盆地陆相大规模优质烃源岩沉积环境的地球化学标志[J].中国科学:地球科学,2011,41(9):1235-1267.
[39]Sinninghe-DamstéJ S,Keely B J,Betts S E,et al.Variations in abundances and distributions of isoprenoid chromans and long-chain alkylbenzenes in sediments of the Mulhouse Basin:A molecular sedimentary record of palaeosalinity[J].Organic Geochemistry,1993,20(8):1201-1215.
[40]Schwark L,Vliex M,Schaeffer P.Geochemical characterization of Malm Zeta laminated carbonates from the Franconian Alb,SW-Germany(II)[J].Organic Geochemistry,1998,29(8):1921-1952.
[41]Bechtel A,Gawlick H J,Gratzer R,et al.Molecular indicators of palaeosalinity and depositional environment of small scale basins within carbonate platforms:The late Triassic Hauptdolomite Wiestalstausee section near Hallein[J].Organic Geochemistry,2007,38(1):92-111.
[42]王丽,宋之光.松辽盆地嫩江组脱羟基维生素E的分布及其地球化学意义[J].地球化学,2010,39(5):469-478.
[43]卢鸿,孙永革,彭平安.轮南油田原油中三甲基苯基类异戊二烯化合物的检出及其意义[J].高校地质学报,2007,10(2):283-289.