东非鲁武马盆地渐新统深水沉积层序地层格架组成和时空分布
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摘要
由于缺乏与陆架边缘的直接联系,深水层序划分在层序地层学研究中成为难点。东非鲁武马盆地渐新统含气砂岩储层为深水沉积环境的重力流沉积,合理的层序地层划分方法可以指导有利目标层系的解释及区域油气勘探。以混合层序地层模型为指导,以三维地震资料应用为主,多种资料综合分析开展深水层序地层学研究,揭示渐新统深水沉积过程和沉积体系的成因联系。根据地层的终止类型、凝缩段、块体搬运沉积等识别层序边界,通过分析沉积物性质、规模以及形成深水沉积的浊流密度差异,确定沉积结构单元与体系域的对应关系,建立渐新统等时地层格架,分析深水沉积演化规律。鲁武马盆地渐新统划分为两个三级层序,强制海退的早期在近陆架边缘陆坡上均形成大规模局部发育的块体搬运沉积,之后在不同层序沉积特征表现出差异性。下渐新统三级层序以粗-中粗砂岩为主、具有高砂/泥比、高密度的大型朵体为强制海退晚期产物。堤化水道体系沉积于低位体系域及海侵早期,顶部为凝缩段沉积,使下渐新统层序具有完整体系域组成;受研究区数据范围影响,上渐新统三级层序缺少大型朵体,层序内缺少下降期体系域晚期沉积,其他体系域内沉积结构单元与下渐新统具有较好的相似性。
It is difficult to divide deep water sequences in sequence stratigraphy study due to a lack of direct connection between the sequence and the shelf margin deposition. The Oligocene gas-bearing sandstones in Ruvuma Basin,East Africa,were deposited by gravity flow in deep water environment. A reasonable sequence stratigraphic division is helpful to the interpretation of favorable targets and regional oil and gas exploration. Under the guidance of the mixed sequence stratigraphic model,we put 3D seismic data into application and comprehensively analyzed multiple data to study the sequence stratigraphy,disclosing the genetic relationship between sedimentary processes and sedimentary systems in deep water environment. Sequence boundaries were identified by the strata termination,condensation section and MTD. Consequently,the corresponding relationship between sedimentary architecture element and system tract was established by analyzing the nature and scale of sediments and density difference of turbidity currents leading to deep water deposition,the Oligocene isochronous stratigraphy framework was established and the rules of deep water sedimentary evolution was analyzed. The Oligocene in Ruvuma Basin can be divided into two third-order sequences,for both of which large-scale MTDs accumulated locally on continental slopes near shelf break in early forced regression. But,the sedimentary characteristics of the two sequences show differences. The large lobes in the Lower Oligocene third-order sequence that are dominated by coarse-medium-coarse-grained sandstones and have large sand/shale ratio and high density are products of late forced regressions. The sediments of the leveed channel system were located in the lowstand system tract( LST) and early transgression,with the condensation section overlying the leveed channel system,all of which contribute to the complete systemtract of the Lower Oligocene sequence. Due to the limited data obtained within the study area,large lobes are absent in the Upper Oligocene third-order sequence,within which there is a lack of late deposition in falling stage system tract( FSST). Besides,the sedimentary architecture elements in other system tracts are quite similar to those of the Lower Oligocene sequences.
It is difficult to divide deep water sequences in sequence stratigraphy study due to a lack of direct connection between the sequence and the shelf margin deposition. The Oligocene gas-bearing sandstones in Ruvuma Basin,East Africa,were deposited by gravity flow in deep water environment. A reasonable sequence stratigraphic division is helpful to the interpretation of favorable targets and regional oil and gas exploration. Under the guidance of the mixed sequence stratigraphic model,we put 3D seismic data into application and comprehensively analyzed multiple data to study the sequence stratigraphy,disclosing the genetic relationship between sedimentary processes and sedimentary systems in deep water environment. Sequence boundaries were identified by the strata termination,condensation section and MTD. Consequently,the corresponding relationship between sedimentary architecture element and system tract was established by analyzing the nature and scale of sediments and density difference of turbidity currents leading to deep water deposition,the Oligocene isochronous stratigraphy framework was established and the rules of deep water sedimentary evolution was analyzed. The Oligocene in Ruvuma Basin can be divided into two third-order sequences,for both of which large-scale MTDs accumulated locally on continental slopes near shelf break in early forced regression. But,the sedimentary characteristics of the two sequences show differences. The large lobes in the Lower Oligocene third-order sequence that are dominated by coarse-medium-coarse-grained sandstones and have large sand/shale ratio and high density are products of late forced regressions. The sediments of the leveed channel system were located in the lowstand system tract( LST) and early transgression,with the condensation section overlying the leveed channel system,all of which contribute to the complete systemtract of the Lower Oligocene sequence. Due to the limited data obtained within the study area,large lobes are absent in the Upper Oligocene third-order sequence,within which there is a lack of late deposition in falling stage system tract( FSST). Besides,the sedimentary architecture elements in other system tracts are quite similar to those of the Lower Oligocene sequences.
引文
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[4] Xian B,An S,Wang L,et al. Lacustrine deep-water sequence stratigraphy and prediction model of gravity flow deposits:a case study of shahejie formation in dongyingdepression,Bohai Bay Basin,China[C]∥Abstracts Book of 19th International Sedimentological Congress. Geneva:University of Geneva,2014:762.
[5]徐长贵,杜晓峰,徐伟,等.沉积盆地“源-汇”系统研究新进展[J].石油与天然气地质,2017,38(1):1-11.Xu Changgui,Du Xiaofeng,Xu Wei,et al. New advances of the“Source-to-Sink”system research in sedimentary basins[J]. Oil&Gas Geology,2017,38(1):1-11.
[6]吴因业,张天枢,张志杰,等.沉积体系域类型、特征及石油地质意义[J].古地理学报,2010,12(1):69-81.Wu Yinye,Zhang Tianshu,Zhang Zhijie,et al. Types and characteristics of depositional systems tract and its petroleum geological significance[J]. Journal of Palaeogeography,2010,12(1):69-81.
[7]张光亚,刘小兵,温志新,等.东非被动大陆边缘盆地构造—沉积特征及其对大气田富集的控制作用[J].中国石油勘探,2015,20(4):71-80.Zhang Guangya,Liu Xiaobing,Wen Zhixin,et al. structural and sedimentary characteristics of passive continental margin basins in East Africa and their effect on the formation of giant gas fields[J]. China Petroleum Exploration,2015,20(4):71-80.
[8]许志刚,韩文明,孙玉梅.东非大陆边缘构造演化过程与油气勘探潜力[J].中国地质,2014,41(3):961-969.Xu Zhigang,Han Wenming,Sun Yumei. Tectonic evolution and petroleum exploration prospect East Africa[J]. Geology in China,2014,41(3):961-969.
[9] HIS Energy. Basin monitors:Ruvuma basin[M]. Houston:IHS Inc,2009.
[10] Salman G,Abdula L. Development of the Mozambique and Ruvuma sedimentary basins,offshore Mozambique[J]. Sediment Geology,1995,96(1-2):7-41.
[11]温志新,王兆明,宋成鹏,等.东非被动大陆边缘盆地结构构造差异与油气勘探[J].石油勘探与开发,2015,42(5):671-680.Wen Zhixin,Wang Zhaoming,Song Chengpeng,et al. Structural architecture difference and petroleum exploration of passive continental margin basins in east Africa[J]. Petroleum Exploration and Development,2015,42(5):671-680.
[12] Cochran J R. Himalayan uplift,sea level,and the record of Bengal Fan sedimentation at ODP leg 116 sites[C]∥Cochran J R,Stow D A V,Proceedings of the ocean drilling program scientific results,USA:A&M University Press,1990:397-414.
[13] Haq B U,Hardenbol J,Vail P R. Chronology of fluctuating sea levels since the Triassic[J]. Science,1987,235(4397):1156-1167.
[14] Payton C E. Seismic stratigraphy-application to hydrocarbon exploration[M]∥American Association of Petroleum Geologists Memoir,Tulsa:American Association of Petroleum Geologists,1977,26:3-14.
[15] Catuneanu O. Principles of sequence stratigraphy[M]. Italy:Elsevier,2006:1-375.
[16] Hunt D,Tucker M E. Stranded parasequences and the forced regres-sive wedge systems tract:deposition during baselevel fall[J]. Sedimentary Geology,1992,81(1/2):1-9.
[17] Hunt D,Tucker M E. Stranded parasequences and the forced regressive wedge systems tract:deposition during baselevel fall-reply[J].Sedimentary Geology,1995,95(1/2):147-160.
[18] Posamentier H W,Vail P R. Eustatic controls on clastic depositionⅡ-sequence and systems tract models[M]∥Wilgus C K,Ross C A,Posamentier H W. Sea level changes:An integrated approach,SEPM Special Publication. Tulsa:The Society of Economic Paleontologists and Mineralogists,1988:125-154.
[19] Posamentier H W,Allen G P. Siliciclastic sequence stratigraphy:concepts and applications[M]∥SEPM. Concepts in sedimentology and paleontology. Tulsa:Society for Sedimentary Geology,1999,7:210.
[20] Posamentier H W,Kolla V. Seismic geomorphology and stratigraphy of depositional elements in deep-water settings[J]. Journal of Sedimentary Research,2003,73(3):367-388.
[21]庞雄,陈长民,彭大钧,等.南海珠江深水扇系统的层序地层学研究[J].地学前缘,2007,14(1):220-229.Pang Xiong,Chen Changmin,Peng Dajun,et al. Sequence stratigraphy of pearl river deep-water fan system in the South China Sea[J].Earth Science Frontiers,2007,14(1):220-229.
[22] Posamentier H W,Jervey M T,Vail P R. Eustatic controls on clastic depositionⅠ-conceptual framework[M]∥Wilgus C K,Ross C A,Posamentier H W. Sea level changes:An integrated approach,SEPM Special Publication. Tulsa:The Society of Economic Paleontologists and Mineralogists,1988:109-124.
[23] Kolla V,Posamentier H W,Eichenseer H. Stranded parasequences and the forced regressive wedge systems tract:deposition during baselevel fall-discussion[J]. Sedimentary Geology,1995,95(1-2):139-145.
[24] Mitchum R M,Jr. Seismic stratigraphy and global changes of sea level,part 11:glossary of terms used in seismic stratigraphy[M]∥Payton C E. Seismic stratigraphy-Applications to hydrocarbon exploration,memoir. Tulsa,OK:American Association of Petroleum Geologists,1977:205-212.
[25]秦雁群,万仑坤,计智锋,等.深水块体搬运沉积体系研究进展[J].石油与天然气地质,2018,39(1):140-152.Qin Yanqun,Wan Lunkun,Ji Zhifeng,et al. Progress of research on deep-water mass-transport deposits[J]. Oil&Gas Geology,2018,39(1):140-152.
[26] Suzanne B,Joe C,Mads H. A review of kinematics indicators from mass transport complexes using 3D seismic data[J]. Marine and Petroleum Gology,2009,26(7):1132-1151.
[27] Hampton M A. Competence of fine-grained debris flows[J]. Journal of Sedimentary Petrology,1975,45(4):834-844.
[28] Shanmugam G,Moiola R J. Reinterpretation of depositional processes in a classic flysch sequence(Pennsylvanian Jackfork Group),Ouachita Mountains,Arkansas and Oklahoma[J]. AAPG Bulletin,1995,79(5):672-695.
[29] Kuenen P H,Migliorini C I. Turbidity currents as a cause of graded bedding[J]. Journal of Geology,1950,58(2):91-127.
[30]裴羽,何幼斌,李华,等.高密度浊流和砂质碎屑流关系的探讨[J].地质论评,2015,61(6):1281-1292.Pei Yu,He Youbin,Li Hua,et al. Discuss about relationship between high-density turbidity current and sandy debris flow[J]. Geological Review,2015,61(6):1281-1292.
[31] Lowe D R. Sediment-gravity flows,Ⅱ:Depostional models with special reference to the deposits of high-density turbidity currents[J].Journal of Sedimentary Petrology,1982,2(1):279-297.
[32] Mahanjane E S,Franke D. The Rovuma delta deep-water fold-andthrust belt,offshore Mozambique.[J]. Tectonophysics,2014,614(3):91-99.
[33]孙辉,吕福亮,范国章,等.三级层序内受底流影响的富砂深水沉积演化规律-以东非鲁武马盆地中中新统为例[J].天然气地球科学,2017,28(1):106-115.Sun Hui,Lv Fuliang,Fan Guozhang,et al. Evolution of deepwater sand rich sediments Affected by bottom currents in the 3rd order sequences:A case study of Middle Miocene in the Ruvuma Basin[J].Natural Gas Geoscience,2017,28(1):106-115.
[34] Paul N P,Ian K M,Bridget S W,et al. Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania[J]. The Geological Society of America,2008,36(2):179-182.
[35] Bosellini A. East Africa continental margins[J]. Geology,1986,14(1):76-78.
[36] Wa Iford H,White N,Sydow. Solid sediment load history of the Zambezi Delta[J]. Earth and Planetary Science Letters,2005,238(1-2):49-63.
[37] Moore A,Blenkinsop T,Cotterill F W. Southern African topography and erosion history:Plumes or plate tectonics?[J]. Terra Nova,2009,21(4):310-315.
[2]吴因业,朱如凯,罗平,等.沉积学与层序地层学研究新进展:第18届国际沉积学大会综述[J].沉积学报,2011,29(1):199-206.Wu Yinye,Zhu Rukai,Luo Ping,et al. Advance on Sedimentology and sequence stratigraphy:A summary from 18th international sedimentology congress[J]. Acta Sedimentologica Sinica,2011,29(1):199-206.
[3]鲜本忠,朱筱敏,岳大力,等.沉积学研究热点与进展:第19届国际沉积学大会综述[J].古地理学报,2014,16(6):816-826.Xian Benzhong,Zhu Xiaomin,Yue Dali,et al. Current hot topics and advances of sedimentology:A summary from 19th International Sedimentological Congress[J]. Journal of Palaeogeography,2014,16(6):816-826.
[4] Xian B,An S,Wang L,et al. Lacustrine deep-water sequence stratigraphy and prediction model of gravity flow deposits:a case study of shahejie formation in dongyingdepression,Bohai Bay Basin,China[C]∥Abstracts Book of 19th International Sedimentological Congress. Geneva:University of Geneva,2014:762.
[5]徐长贵,杜晓峰,徐伟,等.沉积盆地“源-汇”系统研究新进展[J].石油与天然气地质,2017,38(1):1-11.Xu Changgui,Du Xiaofeng,Xu Wei,et al. New advances of the“Source-to-Sink”system research in sedimentary basins[J]. Oil&Gas Geology,2017,38(1):1-11.
[6]吴因业,张天枢,张志杰,等.沉积体系域类型、特征及石油地质意义[J].古地理学报,2010,12(1):69-81.Wu Yinye,Zhang Tianshu,Zhang Zhijie,et al. Types and characteristics of depositional systems tract and its petroleum geological significance[J]. Journal of Palaeogeography,2010,12(1):69-81.
[7]张光亚,刘小兵,温志新,等.东非被动大陆边缘盆地构造—沉积特征及其对大气田富集的控制作用[J].中国石油勘探,2015,20(4):71-80.Zhang Guangya,Liu Xiaobing,Wen Zhixin,et al. structural and sedimentary characteristics of passive continental margin basins in East Africa and their effect on the formation of giant gas fields[J]. China Petroleum Exploration,2015,20(4):71-80.
[8]许志刚,韩文明,孙玉梅.东非大陆边缘构造演化过程与油气勘探潜力[J].中国地质,2014,41(3):961-969.Xu Zhigang,Han Wenming,Sun Yumei. Tectonic evolution and petroleum exploration prospect East Africa[J]. Geology in China,2014,41(3):961-969.
[9] HIS Energy. Basin monitors:Ruvuma basin[M]. Houston:IHS Inc,2009.
[10] Salman G,Abdula L. Development of the Mozambique and Ruvuma sedimentary basins,offshore Mozambique[J]. Sediment Geology,1995,96(1-2):7-41.
[11]温志新,王兆明,宋成鹏,等.东非被动大陆边缘盆地结构构造差异与油气勘探[J].石油勘探与开发,2015,42(5):671-680.Wen Zhixin,Wang Zhaoming,Song Chengpeng,et al. Structural architecture difference and petroleum exploration of passive continental margin basins in east Africa[J]. Petroleum Exploration and Development,2015,42(5):671-680.
[12] Cochran J R. Himalayan uplift,sea level,and the record of Bengal Fan sedimentation at ODP leg 116 sites[C]∥Cochran J R,Stow D A V,Proceedings of the ocean drilling program scientific results,USA:A&M University Press,1990:397-414.
[13] Haq B U,Hardenbol J,Vail P R. Chronology of fluctuating sea levels since the Triassic[J]. Science,1987,235(4397):1156-1167.
[14] Payton C E. Seismic stratigraphy-application to hydrocarbon exploration[M]∥American Association of Petroleum Geologists Memoir,Tulsa:American Association of Petroleum Geologists,1977,26:3-14.
[15] Catuneanu O. Principles of sequence stratigraphy[M]. Italy:Elsevier,2006:1-375.
[16] Hunt D,Tucker M E. Stranded parasequences and the forced regres-sive wedge systems tract:deposition during baselevel fall[J]. Sedimentary Geology,1992,81(1/2):1-9.
[17] Hunt D,Tucker M E. Stranded parasequences and the forced regressive wedge systems tract:deposition during baselevel fall-reply[J].Sedimentary Geology,1995,95(1/2):147-160.
[18] Posamentier H W,Vail P R. Eustatic controls on clastic depositionⅡ-sequence and systems tract models[M]∥Wilgus C K,Ross C A,Posamentier H W. Sea level changes:An integrated approach,SEPM Special Publication. Tulsa:The Society of Economic Paleontologists and Mineralogists,1988:125-154.
[19] Posamentier H W,Allen G P. Siliciclastic sequence stratigraphy:concepts and applications[M]∥SEPM. Concepts in sedimentology and paleontology. Tulsa:Society for Sedimentary Geology,1999,7:210.
[20] Posamentier H W,Kolla V. Seismic geomorphology and stratigraphy of depositional elements in deep-water settings[J]. Journal of Sedimentary Research,2003,73(3):367-388.
[21]庞雄,陈长民,彭大钧,等.南海珠江深水扇系统的层序地层学研究[J].地学前缘,2007,14(1):220-229.Pang Xiong,Chen Changmin,Peng Dajun,et al. Sequence stratigraphy of pearl river deep-water fan system in the South China Sea[J].Earth Science Frontiers,2007,14(1):220-229.
[22] Posamentier H W,Jervey M T,Vail P R. Eustatic controls on clastic depositionⅠ-conceptual framework[M]∥Wilgus C K,Ross C A,Posamentier H W. Sea level changes:An integrated approach,SEPM Special Publication. Tulsa:The Society of Economic Paleontologists and Mineralogists,1988:109-124.
[23] Kolla V,Posamentier H W,Eichenseer H. Stranded parasequences and the forced regressive wedge systems tract:deposition during baselevel fall-discussion[J]. Sedimentary Geology,1995,95(1-2):139-145.
[24] Mitchum R M,Jr. Seismic stratigraphy and global changes of sea level,part 11:glossary of terms used in seismic stratigraphy[M]∥Payton C E. Seismic stratigraphy-Applications to hydrocarbon exploration,memoir. Tulsa,OK:American Association of Petroleum Geologists,1977:205-212.
[25]秦雁群,万仑坤,计智锋,等.深水块体搬运沉积体系研究进展[J].石油与天然气地质,2018,39(1):140-152.Qin Yanqun,Wan Lunkun,Ji Zhifeng,et al. Progress of research on deep-water mass-transport deposits[J]. Oil&Gas Geology,2018,39(1):140-152.
[26] Suzanne B,Joe C,Mads H. A review of kinematics indicators from mass transport complexes using 3D seismic data[J]. Marine and Petroleum Gology,2009,26(7):1132-1151.
[27] Hampton M A. Competence of fine-grained debris flows[J]. Journal of Sedimentary Petrology,1975,45(4):834-844.
[28] Shanmugam G,Moiola R J. Reinterpretation of depositional processes in a classic flysch sequence(Pennsylvanian Jackfork Group),Ouachita Mountains,Arkansas and Oklahoma[J]. AAPG Bulletin,1995,79(5):672-695.
[29] Kuenen P H,Migliorini C I. Turbidity currents as a cause of graded bedding[J]. Journal of Geology,1950,58(2):91-127.
[30]裴羽,何幼斌,李华,等.高密度浊流和砂质碎屑流关系的探讨[J].地质论评,2015,61(6):1281-1292.Pei Yu,He Youbin,Li Hua,et al. Discuss about relationship between high-density turbidity current and sandy debris flow[J]. Geological Review,2015,61(6):1281-1292.
[31] Lowe D R. Sediment-gravity flows,Ⅱ:Depostional models with special reference to the deposits of high-density turbidity currents[J].Journal of Sedimentary Petrology,1982,2(1):279-297.
[32] Mahanjane E S,Franke D. The Rovuma delta deep-water fold-andthrust belt,offshore Mozambique.[J]. Tectonophysics,2014,614(3):91-99.
[33]孙辉,吕福亮,范国章,等.三级层序内受底流影响的富砂深水沉积演化规律-以东非鲁武马盆地中中新统为例[J].天然气地球科学,2017,28(1):106-115.Sun Hui,Lv Fuliang,Fan Guozhang,et al. Evolution of deepwater sand rich sediments Affected by bottom currents in the 3rd order sequences:A case study of Middle Miocene in the Ruvuma Basin[J].Natural Gas Geoscience,2017,28(1):106-115.
[34] Paul N P,Ian K M,Bridget S W,et al. Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania[J]. The Geological Society of America,2008,36(2):179-182.
[35] Bosellini A. East Africa continental margins[J]. Geology,1986,14(1):76-78.
[36] Wa Iford H,White N,Sydow. Solid sediment load history of the Zambezi Delta[J]. Earth and Planetary Science Letters,2005,238(1-2):49-63.
[37] Moore A,Blenkinsop T,Cotterill F W. Southern African topography and erosion history:Plumes or plate tectonics?[J]. Terra Nova,2009,21(4):310-315.