白云深水区块体搬运沉积体系与水合物分解的相关性研究
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摘要
块体搬运沉积体系(MTDs)作为一种在重力作用下发育的深水沉积体系,在全球大陆边缘广泛分布。鉴于其重要的学术意义和工程意义,近年来成为国内外学者关注的热点。利用南海北部珠江口盆地白云深水区海底多波束地形地貌资料和高分辨率地震反射资料,识别了白云深水区大型块体搬运沉积体系,其分布面积逾10000km2,具有典型块体搬运的结构单元和沉积构造特征,对其开展研究具有重要的理论意义和应用价值。为了进一步探讨MTDs与天然气水合物分解的相关性,分析了水合物的分解机理及其对海底沉积地层的强度产生的影响。建立了研究区海底地质力学模型,并采用极限平衡法对海底斜坡是否稳定做出评价。研究结果表明,白云凹陷北侧的海底峡谷为南侧大型MTDs的发育提供了充足的物源保障,区内水合物的分解对海底MTDs的发育具有诱发作用。
Mass transport deposits(MTDs) are one kind of deepwater sedimentary system driven by gravitation,which widely distributed in the global continental margins.Considering the important academic significance and engineering meaning,MTDs have become a focus of concern by scholars.Based on the multi-beam bathymetric data and high resolution seismic data in Baiyun sag,Pearl river basin,north of South China Sea,we identified large scale MTDs covering over 10,000km2 on the seabed.As Baiyun large scale MTDs with typical structural units,sedimentary and structural features,the research and analysis are of theoretical and applied value.In order to clear further the correlationship between mass transport deposits and the dissociation of gas hydrate,we analysed mechanisms of gas hydrate dissociation and effects on the strength change of submarine sediments.We established geomechanical model and estimated the stability of submarine slope through ultimate equilibrium method.The results show that canyons on the north of Baiyun sag ensure abundant sediment supply while the dissociation of gas hydrate induced the development of MTDs.
Mass transport deposits(MTDs) are one kind of deepwater sedimentary system driven by gravitation,which widely distributed in the global continental margins.Considering the important academic significance and engineering meaning,MTDs have become a focus of concern by scholars.Based on the multi-beam bathymetric data and high resolution seismic data in Baiyun sag,Pearl river basin,north of South China Sea,we identified large scale MTDs covering over 10,000km2 on the seabed.As Baiyun large scale MTDs with typical structural units,sedimentary and structural features,the research and analysis are of theoretical and applied value.In order to clear further the correlationship between mass transport deposits and the dissociation of gas hydrate,we analysed mechanisms of gas hydrate dissociation and effects on the strength change of submarine sediments.We established geomechanical model and estimated the stability of submarine slope through ultimate equilibrium method.The results show that canyons on the north of Baiyun sag ensure abundant sediment supply while the dissociation of gas hydrate induced the development of MTDs.
引文
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[12]龚再升,李思田,谢泰俊等.南海北部大陆边缘盆地分析与油气聚集.北京:科学出版社,1997
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[14]柳保军,袁立忠,申俊等.南海北部陆坡古地貌特征与13.8Ma以来珠江深水扇.沉积学报,2006,24(4):476～452Liu Bao-jun,Yuan Li-zhong,Shen Jun et al.North-ern continental slope palaeogeomorphology and deep-water fan system response of Pearl River since13.8Ma,South China Sea.Acta Sedimentologlca sinica,2006,24(4):476～452
[15]雷新民,张光学,郑艳.南海北部神狐海域天然气水合物形成及分布的地质因素.海洋地质动态,2009,25(5):1～6Lei Xin-min,Zhang Guang-xue,Zheng Yan.Geolog-ic factors of formation and distribution of gas hydratein Shenhu area,northern South China Sea.MarineGeology Letters,2009,25(5):1～6
[16]张光学,祝有海,徐华宁.非活动大陆边缘的天然气水合物及其成藏过程述评.地质论评,2003,49(2):181～187Zhang Guang-xue,Zhu You-hai,Xu Hua-ning.Gashydrate on the passive continental margin and itspool-formation process.Geological Review,2003,49(2):181～187
[17]孙运宝,吴时国,王志君等.南海北部白云大型海底滑坡的几何形态与变形特征.海洋地质与第四纪地质,2008,28(6):69～77Sun Yun-bao,Wu Shi-guo,Wang Zhi-jun et al.Thegeometry and deformation characteristics of Baiyunsubmarine landslide.Marine Geology&QuaternaryGeology,2008,28(6):69～77
[18]龚跃华,杨胜雄,王宏斌等.南海北部神狐海域天然气水合物成藏特征.现代地质,2009,23(2):210～216Gong Yue-hua,Yang Sheng-xiong,Wang Hong-binet al.Gas hydrate reservoir characteristics of ShenhuArea,North Slope of the South China Sea.Geosci-ence,2008,28(6):69～77
[2]Pickering K T and Corregidor J.Mass-transport com-plexes(MTCs)and tectonic control on basin-floorsubmarine fans,middle Eocene,south Spanish Pyre-nees.Journal of Sedimentary Research,2005,75(5):761～783
[3]Frey-Martinez J,Cartwright J,James D.Frontallyconfined versus frontally emergent submarine land-slides:a 3D seismic characterization.MarineandPetroleumGeology,2006,23(5):585～604
[4]Mulder T and Cochonat P.Classification of offshoremass movements.Journal of Sedimentary Re-search,1996,66(1):43～57
[5]Weimer P.Sequence stratigraphy,facies geometries,and depositional history of the Mississippi Fan,Gulfof Mexico.AAPG Bull,1990,74(4):425～453
[6]刘军,庞雄,颜承志等.南海北部陆坡白云深水区深水沉积结构要素.吉林大学学报(地球科学版),2011,41(4):992～998Liu Jun,Pang Xiong,Yan Cheng-zhi et al.Deepwa-ter depositional elements in Baiyun Deepwater Area ofthe northern continental slope,South China Sea.Journal of Jilin University(Earth Science Edition),2011,41(4):992～998
[7]刘锋,吴时国,孙运宝.南海北部陆坡水合物分解引起海底不稳定性的定量分析.地球物理学报,2010,53(4):946～953Liu Feng,Wu Shi-guo,Sun Yun-bao,A quantitativeanalysis for submarine slope instability of the north-ern South China Sea due to gas hydrate dissociation.Chinese J Geophys,2010,53(4):946～953
[8]吴时国,秦蕴珊.南海北部陆坡深水沉积体系研究.沉积学报,2009,27(5):922～930Wu Shi-guo,Qin Yun-shan.The research of deepwaterdepositional system in the Northern South China Sea.Acta Sedimentologica Sinica,2009,27(5):922～930
[9]Grozic J L H and Kvalstad T J.Effect of gas ondeepwater marine sediments.In Proceedings ofXVth International Conference on Soil Mechanicand Geotechnical Engineering,2001,27～31
[10]Nixon M F.Influence of gas hydrates on submarineslope stability[M],Department of Civil engineering,University of Calagary,Alberta,2005
[11]柳保军,庞雄,颜承志等.珠江口盆地白云深水区渐新世中新世陆架坡折带演化及油气勘探意义.石油学报,2011,32(2):234～242Liu Bao-jun,Pang Xiong,Yan Cheng-zhi et al.Evolu-tion of the Oligocene Miocene shelf slope break zone inthe Baiyun deep water area of the Pearl River Mouth Ba-sin and its significance in oil gas exploration.Acta Petro-lei Sinica,2011,32(2):234～242
[12]龚再升,李思田,谢泰俊等.南海北部大陆边缘盆地分析与油气聚集.北京:科学出版社,1997
[13]朱伟林,张功成,杨少坤等.南海北部大陆边缘盆地天然气地质.北京:石油工业出版社,2007
[14]柳保军,袁立忠,申俊等.南海北部陆坡古地貌特征与13.8Ma以来珠江深水扇.沉积学报,2006,24(4):476～452Liu Bao-jun,Yuan Li-zhong,Shen Jun et al.North-ern continental slope palaeogeomorphology and deep-water fan system response of Pearl River since13.8Ma,South China Sea.Acta Sedimentologlca sinica,2006,24(4):476～452
[15]雷新民,张光学,郑艳.南海北部神狐海域天然气水合物形成及分布的地质因素.海洋地质动态,2009,25(5):1～6Lei Xin-min,Zhang Guang-xue,Zheng Yan.Geolog-ic factors of formation and distribution of gas hydratein Shenhu area,northern South China Sea.MarineGeology Letters,2009,25(5):1～6
[16]张光学,祝有海,徐华宁.非活动大陆边缘的天然气水合物及其成藏过程述评.地质论评,2003,49(2):181～187Zhang Guang-xue,Zhu You-hai,Xu Hua-ning.Gashydrate on the passive continental margin and itspool-formation process.Geological Review,2003,49(2):181～187
[17]孙运宝,吴时国,王志君等.南海北部白云大型海底滑坡的几何形态与变形特征.海洋地质与第四纪地质,2008,28(6):69～77Sun Yun-bao,Wu Shi-guo,Wang Zhi-jun et al.Thegeometry and deformation characteristics of Baiyunsubmarine landslide.Marine Geology&QuaternaryGeology,2008,28(6):69～77
[18]龚跃华,杨胜雄,王宏斌等.南海北部神狐海域天然气水合物成藏特征.现代地质,2009,23(2):210～216Gong Yue-hua,Yang Sheng-xiong,Wang Hong-binet al.Gas hydrate reservoir characteristics of ShenhuArea,North Slope of the South China Sea.Geosci-ence,2008,28(6):69～77