墨西哥湾—南海海底表层沉积物中有机质组成与分布特征研究
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摘要
该博士论文通过对海底富集天然气水合物的墨西哥湾海底表层沉积物样品和我国南海海底表层沉积物样品在有机质组成、分布和特殊生物标记物及其碳同位素等方面的对比研究,对烷烃(正构烷烃、类异戊二烯烃、环烷烃和支链烷烃)、多环芳烃、脂肪醇、脂肪酸等的有机化合物组成、分布和来源以及有机地球化学的意义进行了初步探讨。该项研究对于现代沉积有机地球化学及我国南海海域海底天然气水合物的研究和勘探具有积极的理论和实际意义。论文取得了以下主要认识:
1、墨西哥湾沉积物样品中有机碳含量变化范围在0.20-1.21%之间。可溶有机质主要由饱和烃、芳烃和非烃组成,均无沥青质。从可溶有机质族组成相对关系显示,墨西哥湾沉积物可分为两组,一组是具有典型现代海洋沉积有机质组成特点的样品,族组成呈:饱和烃<芳烃<非烃;另一组样品中可溶有机质则具有原油族组成特点,呈饱和烃>>非烃>芳烃,显示了受海底原油渗漏污染的特点。而所研究的南海沉积物样品中可溶有机质族以非烃为主,含量在80%—90%之间,族组成呈饱和烃<芳烃<<非烃。此外,墨西哥湾沉积物中可溶有机质呈原油组成特点的样品具有相对高含量的UCM,表明遭受了强烈生物降解作用。
2、在墨西哥湾S-1和S-4沉积物样品中检测到一组具有2,6,10,15,19—五甲基二十烷烯结构的含多个不饱和双键的烯烃化合物(pentamethylicosenes,PMIA)它们的碳同位素值在-86.7‰—-115.5‰之间,是甲烷古细菌厌氧氧化所生成的指征性标志物,标志着该沉积物所在区域可能有海底天然气渗漏、甚至有天然气水合物的产出。
3、墨西哥湾沉积物样品中正构烷烃主要呈双峰型—前峰偶碳优势后峰奇碳优势、双峰型—前峰无奇偶优势后峰奇碳优势和单峰型的分布模式。而南海沉积物样品中的正构烷烃主要呈双峰型—前峰偶碳优势后峰奇碳优势和单峰型的分布模式。所分析的墨西哥湾和南海大部分积沉积物样品中的正构烷烃多以低碳数分布占绝对优势,显示了以低等生物为主的有机母质来源,中等长链环烷烃和支链烷烃的检出也说明低等生物是主要的有机母质来源。
The composition, distribution of organic matter and specific biomarkers and their carbon isotopic composition in the sea floor sediments from the Gulf of Mexico where the oil and gas seeps and gas hydrate are in abundance and the South China Sea were comparatively studied in this thesis. The composition and distribution of aliphatics, aromatics, alcohols and fatty acids and their organic geochemical significance were discussed in details. This study is both theoretical and practical useful to the modern organic geochemistry and to the investigation and exploration of gas hydrate occurrence in the South China Sea. The following major conclusions can be drawn from this study:1. The contents of total organic carbon (TOC) varied form 0.20%-1.21 % in the sediment from the Gulf of Mexico. The extractable organic matter is mainly composed of aliphatic hydrocarbon, aromatic hydrocarbon and polar hydrocarbon and virtually contains no asphaltene. The sediments could be divided into two groups according to the relative abundance of hydrocarbon composition of extractable organic matter: the first group of samples shows the characteristic of typical modern organic matters as it displays an order of aliphatics < aromatics ? polar;the second group of samples is assembly the hydrocarbon composition of crude oil as it shows an order of aliphatics ? aromatics >polar. While the hydrocarbon composition of extractable organic matter in the sediments from the South China Sea is dominated by polar fraction with a content of 80%~90%, and the hydrocarbon composition displays an order of aliphatics unsaturated double bonds has been identified in the samples of S-l and S-4 from the Gulf of Mexico and their 513C values are very much depleted in 13C and ranged from -86.7 to -115.5%o. These unsaturated PMIA compounds are typical biomarkers derived from the anaerobic oxidation of methane mediated by methane-oxidizing archaeal bacteria and indicative of the gas seeps or the occurrence of gas hydrates in the sea floor sediments.3. The distribution of n-alkanes in the sediments from the Gulf of Mexico show two patterns: bimodal and unimodal. One distribution pattern of bimodal characterized by even carbon preference in front-peak group and odd carbon preference in back-peak group;while the other distribution pattern of bimodal characterized by no carbon preference in front-peak group and odd carbon preference in back-peak group. However, The distribution of n-alkanes in the sediments from the South China Sea could be only divided into two patterns: bimodal with even carbon preference in front-peak group and odd carbon preference in back-peak group and unimodal. The distribution of n-alkanes dominated by low molecular weight alkanes in most samples from the Gulf of Mexico and South China sea, as well as the identification of branched and cyclic hydrocarbons with medium-chain, are indicative of lower organism sourced organic inputs.4.Naphthalenes are dorminant aromatic compounds followed by phenanthrenes and dibenzothiophenes in the sediments from the Gulf of Mexico, while phenanthrenes are dorminant aromatic compounds followed by biphenyls and phenanthrenes in the most samples of the South China Sea. These prameters of LMW/HWM and Ph/An are indicative of that most sediments were contaminated by the oil seeps or other sourced petroleum pollution.5. The differences in the compositions and distribution of alcohols between the samples from the Gulf of Mexico and South China Sea mainly reflected the diversity of source inputs of parent materials, sedimentary environments, the microorganism speciation and their biogeochemical processes. The distribution of n-alcohols on the gas chromatograms for most samples from the Gulf of Mexico was dominated by heavy molecular weight compounds, which indicates a typical input of higher plants,
while the distribution of n-alcohols on the gas chromatograms of the samples from the South China Sea dominated mainly by low molecular weight compounds and reflects a low organism sourced inputs such as microbial and phytoplankton.6. The composition and distribution of fatty acids and their related ratios suggest that the microbial and phytoplankton were major sources for these compounds, while the higher plants are also an important source for some samples.
1、墨西哥湾沉积物样品中有机碳含量变化范围在0.20-1.21%之间。可溶有机质主要由饱和烃、芳烃和非烃组成,均无沥青质。从可溶有机质族组成相对关系显示,墨西哥湾沉积物可分为两组,一组是具有典型现代海洋沉积有机质组成特点的样品,族组成呈:饱和烃<芳烃<非烃;另一组样品中可溶有机质则具有原油族组成特点,呈饱和烃>>非烃>芳烃,显示了受海底原油渗漏污染的特点。而所研究的南海沉积物样品中可溶有机质族以非烃为主,含量在80%—90%之间,族组成呈饱和烃<芳烃<<非烃。此外,墨西哥湾沉积物中可溶有机质呈原油组成特点的样品具有相对高含量的UCM,表明遭受了强烈生物降解作用。
2、在墨西哥湾S-1和S-4沉积物样品中检测到一组具有2,6,10,15,19—五甲基二十烷烯结构的含多个不饱和双键的烯烃化合物(pentamethylicosenes,PMIA)它们的碳同位素值在-86.7‰—-115.5‰之间,是甲烷古细菌厌氧氧化所生成的指征性标志物,标志着该沉积物所在区域可能有海底天然气渗漏、甚至有天然气水合物的产出。
3、墨西哥湾沉积物样品中正构烷烃主要呈双峰型—前峰偶碳优势后峰奇碳优势、双峰型—前峰无奇偶优势后峰奇碳优势和单峰型的分布模式。而南海沉积物样品中的正构烷烃主要呈双峰型—前峰偶碳优势后峰奇碳优势和单峰型的分布模式。所分析的墨西哥湾和南海大部分积沉积物样品中的正构烷烃多以低碳数分布占绝对优势,显示了以低等生物为主的有机母质来源,中等长链环烷烃和支链烷烃的检出也说明低等生物是主要的有机母质来源。
The composition, distribution of organic matter and specific biomarkers and their carbon isotopic composition in the sea floor sediments from the Gulf of Mexico where the oil and gas seeps and gas hydrate are in abundance and the South China Sea were comparatively studied in this thesis. The composition and distribution of aliphatics, aromatics, alcohols and fatty acids and their organic geochemical significance were discussed in details. This study is both theoretical and practical useful to the modern organic geochemistry and to the investigation and exploration of gas hydrate occurrence in the South China Sea. The following major conclusions can be drawn from this study:1. The contents of total organic carbon (TOC) varied form 0.20%-1.21 % in the sediment from the Gulf of Mexico. The extractable organic matter is mainly composed of aliphatic hydrocarbon, aromatic hydrocarbon and polar hydrocarbon and virtually contains no asphaltene. The sediments could be divided into two groups according to the relative abundance of hydrocarbon composition of extractable organic matter: the first group of samples shows the characteristic of typical modern organic matters as it displays an order of aliphatics < aromatics ? polar;the second group of samples is assembly the hydrocarbon composition of crude oil as it shows an order of aliphatics ? aromatics >polar. While the hydrocarbon composition of extractable organic matter in the sediments from the South China Sea is dominated by polar fraction with a content of 80%~90%, and the hydrocarbon composition displays an order of aliphatics
while the distribution of n-alcohols on the gas chromatograms of the samples from the South China Sea dominated mainly by low molecular weight compounds and reflects a low organism sourced inputs such as microbial and phytoplankton.6. The composition and distribution of fatty acids and their related ratios suggest that the microbial and phytoplankton were major sources for these compounds, while the higher plants are also an important source for some samples.
引文
浮溪,杨木桩,文鹏飞等.南海天然气水合物地震资料处理及其特征.地震科技情报,2001,20(4):33-40.
龚建民,杨文达.东海天然气水合物的区域地质特征及可能的远景区.海洋地质动态,2001,7(7):20-23.
栾锡武,赵一阳.海洋沉积物中的天然气水合物中及其在我国边缘海域的研究进展.Marine Science.2001,6(25):23-25
卢振全,张祖基等.南海临震前卫星热红外线增温异常原因初探.地球学报,2002,23(1):42-46.
卢振全,龚建民等.东海天然气水合物的地球化学标志与找矿远景.海洋地质与第四纪地质,2003,23(3):77-81.
孟仟祥,张松林,崔明中等.不同沉积环境湖相低熟原油的分布特征.沉积学报,1999,17(1):112-121.
孟宪伟,刘保华,石学法等.冲深海槽中段西陆坡下缘天然气水合物存在的可能性分析.沉积学报,2000,18,(4):629-633.
姚伯初.南海北部陆缘天然气水合物初探.海洋地质与第四纪地质,1998,18(4):11-18.
姚伯初.南海的天然气水合物矿藏.热带海洋学报,2001,20(2):20-28.
宋海斌,耿建华等.南海北部东海海域天然气水合物的初步研究.地球物理学报,2001,44(5):687-695.
张光学,黄永祥等.南海天然气水合物的成矿远景.海洋地质与第四纪地质,2002,22(1):75-81.
祝有海,张光学等.南海天然气水合物成矿条件与找矿前景.石油学报,2001,22(5):6-12.
Alexei V.M., Sassen R. Preliminary assessment of resources and economic potential of individual gas hydrate accumulations in the Gulf of Mexico continental slope.Marine and Petroleum Geology, 2003.20:111-128
Bian L. Isotopic Biogeochemistry of Individual Com-pounds in a Modem Coastal Marine Sediment (Kattegat,Denmark and Sweden). MSc thesis, Department of Geological Sciences, Indiana University, 1994.
Brassell S.C., Wardroper A.M.K., Thomson J.R., et al. Specific acyclic isoprenoids asbiological markers of methanogenic bacteria in marine sediments. Nature, 1981, 290:693-696.
Chen Duofu, Huang Yongyang, Yuan Xunlai , Cathles L.M. Seep carbonates and preserved methane oxidizing archaea and sulfate reducing bacteria fossils suggest recent gas venting on the seafloor in the Northeastern South China Sea. Marine and Petoleum Geology, 2005, inpress.
Chi W.C., Reed D. L., Liu C.S., et al. Distribution of the bottom-simulating reflector in the offshore Taiwan collision zone. Terrestrial Atmosphere and Oceanic Sciene,1998,9(4):779-794.
Cranwell P.A.. Decomposition of aquatic biota and sediment formation: organic compounds in detritus resulting from microbial attack on the alga, Cerium hirundinella.Freshwater Biol., 1976, 6:41 - 48.
Elvert M, Suess E., Whiticar M.J. Anaerobic methane oxidation associated with marine gas hydrates: superlight C-isotopes from saturated and unsaturated C_(20) and C_(25) irregular isoprenoids. Naturwissenschaften, 1999,86:295-300.
Hinrichs K.-U., Hayes J.M., Sylva S.P., Brewer P.G., DeLong E.F. ethane consuming archaebacteria in marine sediments. Nature, 1999,398:802-805.
Hinrichs K.-U., Roger E. Summons.Molecular and isotopic analysis of anaerobic methane oxidizing communities in marine sediments. Organic Geochemistry, 2000,31:685-1701.
Hoehler T.M., Alperin M.J., Albert D.B., Martens C.S. Field and laboratory studies of methane oxidation in an anoxic marine sediment: Evidence for a methanogen-sulfate reducer consortium. Global Biogeochemical Cycles, 1994, 8: 451-463.
Kvenvolden K.A. A review of the geochemistry of methane in natural gas hydrate. Organic Geochemistry, 1995,23: 997-1008.
MacDonald I. R., Guinasso J. N .L. Sassen R., et al. Gas hydrate that breaches the sea floor on the continental slope of the Gulf of Mexico. Geology,1994, 22:699-702.
MacDonald I.R., William W.S., Michael B.P. Gas hydrate and osynthetic- biota in mounded bathymetry at mid-slope hydrocarbon seeps Northern Gulf of Mexico. Marine Geology, 2003, 198:133-158
Pace N.R. Molecular view of microbial diversity and the biosphere. Science, 1997 276: 734-740.
Parkes R.J., Cragg B.A., Bale S.J., Getlii J.M., Goodman K., Rochelle P.A., Fry J.C., Weightman A.J., Harvey S.M. Deep bacterial biosphere in pacicc-ocean sediments. Nature, 1994,371:410-413.
Parkes R.J., Cragg B.A., Wellsbury P. Recent studies on bacterial populations in subsea(?)oor sediments: A review. Hydrogeol.J., 2000,8: 11-28.
Pancost R.D., Sinninghe D.J.S., Maarel M.J.E.C., et al. Biomarker evidence for widespread anaerobic methane oxidation in Mediterranean sediments by a consortium of methanogenic archaea and bacteria. Applied and Environmental Microbiology, 2000, 6: 1126:1132.
Pancost R.D., Chopmans E., Sinninghe J. S. Archaeal lipids in Mediterranean Cold Seeps: Molecular proxies for anaerobic methane oxidation. Geochimica et Cosmochimica Acta, 2001, 65(10):1611-1627.
Sassen R., MacDonald I.R. Evidence of structure H hydrate, Gulf of Mexico continental slope. Organic Geochemistry, 1994, 23:1029-1032
Sassen R., Tephen T., Sweeta D. A., et al. Gas hydrate and crude oil from the Mississippi Fan Foldbelt, downdip Gulf of Mexico Salt Basin: significance to petroleum system. Organic Geochemistry, 2001,32:999-1008
Sassen R., Harry H., Roberts C, et al. Free hydrocarbon gas, gas hydrate, and authigenic minerals in chemo synthetic communities of the northern Gulf of Mexico continental slope: relation to microbial processes. Chemical Geology, 2004, 205: 195-217.
Thiel V., Peckmann J. Molecular signals for anaerobic methane oxidation in Black Sea seep carbonates and a microbial mat. Marine Chemistry, 2001, 73: 97-112..
Wellsbury P., Goodman K., Barth T., Cragg B.A., Barnes S.P., Parkes, R.J. Deep marine biosphere fuelled by increasing organic matter availability during burial and heating. Nature, 1997,388: 573-576.
Zhang C.L., Li Y., Wall J.D., et al. Lipid and carbon isotopic evidence of methane oxidizing and sulfate-reducing bacteria in association with gas hydrates from the Gulf of Mexico. Geology, 2002, 30: 239-242.
Zhang C L, Pancost R.D., Sassenc R., et al. Archaeal lipid biomarkers and isotopic evidence of anaerobic methane oxidation associated with gas hydrates in the Gulf of Mexico. Organic Geochemistry, 2003,34: 827-836.
Reeburgh W.S. "Soft spots" in the global methane budget. In: Lidstrom, M.E., Tabita, F.R. (Eds.), Microbial Growth on C1 compounds. Kluwer Academic Publishers, Dordrecht, 1996,334-342.
龚建民,杨文达.东海天然气水合物的区域地质特征及可能的远景区.海洋地质动态,2001,7(7):20-23.
栾锡武,赵一阳.海洋沉积物中的天然气水合物中及其在我国边缘海域的研究进展.Marine Science.2001,6(25):23-25
卢振全,张祖基等.南海临震前卫星热红外线增温异常原因初探.地球学报,2002,23(1):42-46.
卢振全,龚建民等.东海天然气水合物的地球化学标志与找矿远景.海洋地质与第四纪地质,2003,23(3):77-81.
孟仟祥,张松林,崔明中等.不同沉积环境湖相低熟原油的分布特征.沉积学报,1999,17(1):112-121.
孟宪伟,刘保华,石学法等.冲深海槽中段西陆坡下缘天然气水合物存在的可能性分析.沉积学报,2000,18,(4):629-633.
姚伯初.南海北部陆缘天然气水合物初探.海洋地质与第四纪地质,1998,18(4):11-18.
姚伯初.南海的天然气水合物矿藏.热带海洋学报,2001,20(2):20-28.
宋海斌,耿建华等.南海北部东海海域天然气水合物的初步研究.地球物理学报,2001,44(5):687-695.
张光学,黄永祥等.南海天然气水合物的成矿远景.海洋地质与第四纪地质,2002,22(1):75-81.
祝有海,张光学等.南海天然气水合物成矿条件与找矿前景.石油学报,2001,22(5):6-12.
Alexei V.M., Sassen R. Preliminary assessment of resources and economic potential of individual gas hydrate accumulations in the Gulf of Mexico continental slope.Marine and Petroleum Geology, 2003.20:111-128
Bian L. Isotopic Biogeochemistry of Individual Com-pounds in a Modem Coastal Marine Sediment (Kattegat,Denmark and Sweden). MSc thesis, Department of Geological Sciences, Indiana University, 1994.
Brassell S.C., Wardroper A.M.K., Thomson J.R., et al. Specific acyclic isoprenoids asbiological markers of methanogenic bacteria in marine sediments. Nature, 1981, 290:693-696.
Chen Duofu, Huang Yongyang, Yuan Xunlai , Cathles L.M. Seep carbonates and preserved methane oxidizing archaea and sulfate reducing bacteria fossils suggest recent gas venting on the seafloor in the Northeastern South China Sea. Marine and Petoleum Geology, 2005, inpress.
Chi W.C., Reed D. L., Liu C.S., et al. Distribution of the bottom-simulating reflector in the offshore Taiwan collision zone. Terrestrial Atmosphere and Oceanic Sciene,1998,9(4):779-794.
Cranwell P.A.. Decomposition of aquatic biota and sediment formation: organic compounds in detritus resulting from microbial attack on the alga, Cerium hirundinella.Freshwater Biol., 1976, 6:41 - 48.
Elvert M, Suess E., Whiticar M.J. Anaerobic methane oxidation associated with marine gas hydrates: superlight C-isotopes from saturated and unsaturated C_(20) and C_(25) irregular isoprenoids. Naturwissenschaften, 1999,86:295-300.
Hinrichs K.-U., Hayes J.M., Sylva S.P., Brewer P.G., DeLong E.F. ethane consuming archaebacteria in marine sediments. Nature, 1999,398:802-805.
Hinrichs K.-U., Roger E. Summons.Molecular and isotopic analysis of anaerobic methane oxidizing communities in marine sediments. Organic Geochemistry, 2000,31:685-1701.
Hoehler T.M., Alperin M.J., Albert D.B., Martens C.S. Field and laboratory studies of methane oxidation in an anoxic marine sediment: Evidence for a methanogen-sulfate reducer consortium. Global Biogeochemical Cycles, 1994, 8: 451-463.
Kvenvolden K.A. A review of the geochemistry of methane in natural gas hydrate. Organic Geochemistry, 1995,23: 997-1008.
MacDonald I. R., Guinasso J. N .L. Sassen R., et al. Gas hydrate that breaches the sea floor on the continental slope of the Gulf of Mexico. Geology,1994, 22:699-702.
MacDonald I.R., William W.S., Michael B.P. Gas hydrate and osynthetic- biota in mounded bathymetry at mid-slope hydrocarbon seeps Northern Gulf of Mexico. Marine Geology, 2003, 198:133-158
Pace N.R. Molecular view of microbial diversity and the biosphere. Science, 1997 276: 734-740.
Parkes R.J., Cragg B.A., Bale S.J., Getlii J.M., Goodman K., Rochelle P.A., Fry J.C., Weightman A.J., Harvey S.M. Deep bacterial biosphere in pacicc-ocean sediments. Nature, 1994,371:410-413.
Parkes R.J., Cragg B.A., Wellsbury P. Recent studies on bacterial populations in subsea(?)oor sediments: A review. Hydrogeol.J., 2000,8: 11-28.
Pancost R.D., Sinninghe D.J.S., Maarel M.J.E.C., et al. Biomarker evidence for widespread anaerobic methane oxidation in Mediterranean sediments by a consortium of methanogenic archaea and bacteria. Applied and Environmental Microbiology, 2000, 6: 1126:1132.
Pancost R.D., Chopmans E., Sinninghe J. S. Archaeal lipids in Mediterranean Cold Seeps: Molecular proxies for anaerobic methane oxidation. Geochimica et Cosmochimica Acta, 2001, 65(10):1611-1627.
Sassen R., MacDonald I.R. Evidence of structure H hydrate, Gulf of Mexico continental slope. Organic Geochemistry, 1994, 23:1029-1032
Sassen R., Tephen T., Sweeta D. A., et al. Gas hydrate and crude oil from the Mississippi Fan Foldbelt, downdip Gulf of Mexico Salt Basin: significance to petroleum system. Organic Geochemistry, 2001,32:999-1008
Sassen R., Harry H., Roberts C, et al. Free hydrocarbon gas, gas hydrate, and authigenic minerals in chemo synthetic communities of the northern Gulf of Mexico continental slope: relation to microbial processes. Chemical Geology, 2004, 205: 195-217.
Thiel V., Peckmann J. Molecular signals for anaerobic methane oxidation in Black Sea seep carbonates and a microbial mat. Marine Chemistry, 2001, 73: 97-112..
Wellsbury P., Goodman K., Barth T., Cragg B.A., Barnes S.P., Parkes, R.J. Deep marine biosphere fuelled by increasing organic matter availability during burial and heating. Nature, 1997,388: 573-576.
Zhang C.L., Li Y., Wall J.D., et al. Lipid and carbon isotopic evidence of methane oxidizing and sulfate-reducing bacteria in association with gas hydrates from the Gulf of Mexico. Geology, 2002, 30: 239-242.
Zhang C L, Pancost R.D., Sassenc R., et al. Archaeal lipid biomarkers and isotopic evidence of anaerobic methane oxidation associated with gas hydrates in the Gulf of Mexico. Organic Geochemistry, 2003,34: 827-836.
Reeburgh W.S. "Soft spots" in the global methane budget. In: Lidstrom, M.E., Tabita, F.R. (Eds.), Microbial Growth on C1 compounds. Kluwer Academic Publishers, Dordrecht, 1996,334-342.