南海北部陆坡神狐海域浅地层与单道地震剖面联合解释——水合物区沉积地层特征
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摘要
本文通过南海北部陆坡神狐海域浅地层、单道地震剖面联合解释,发现了一系列与天然气水合物密切相关的海底异常地貌、地层结构。在精细浅地层剖面上发现了陆坡丘状体、浅部断层以及由连续强反射层、声空白补丁、局部增强反射和声空白带构成的海底浅部含气带。浅部含气带位于海底之下34—82m,通过其空间分布位置判断,认为气体来源于深部天然气水合物的分解。在单道地震剖面上识别出麻坑、气体渗漏柱、褶皱、模拟海底反射(BSR,bottom simulating reflector)等结构。BSR位于我国首次钻取的天然气水合物样品深度之下,判断其为该区水合物稳定带底界。依据ODP1148站深海钻井的地层厚度、沉积速率、测年等资料进行地层划分,识别出渐新世、中新世等地层界面,初步建立了神狐海域水合物区沉积地层年代标尺。地层年代划分结果表明BSR、褶皱、首次钻取的水合物样品位于晚中新世至上新世地层内,以上地层成为南海北部神狐海域天然气水合物勘探重点目标层位。
The study area of this paper is the slope of the Shenhu Area in the northern South China Sea.We interpreted both sub-bottom and single-channel seismic profiles to describe the acoustic characteristics of gas hydrate sediment and to discuss the cause of its formation.We distinguished some abnormal physiognomy and geologic objects that are relevantrelative to gas hydrate in profiles.Protuberance,shallow fault,acoustic blank patch,partial enhanced reflection and acoustic blank zone were discovered in the legible sub-bottom profile.The shallow gassy belt locates under the seabed from 34 to 82m.Contrasting the sub-bottom profile with the data of China’s first gas hydrate expedition,we believed that the gas in the shallow gassy belt came from the decompounding of deeper gas hydrate.Pockmark,seepage,drape and Bottom Simulating Reflector(BSR)were recognized in the single-channel seismic profile.The depth of BSR is slightly deeper than that for the sample of China’s first gas hydrate expedition in the study area.The BSR in the seismic profile might be the bottom of gas hydrate.Based on the time-depth conversion,we plotted out Oligocene,early Miocene epoch,middle Miocene epoch and Pliocene in the seismic profile according to the sediment depth,sediment speed and age of ODP1148 and set up the chronology of the gas hydrate sediment.
The study area of this paper is the slope of the Shenhu Area in the northern South China Sea.We interpreted both sub-bottom and single-channel seismic profiles to describe the acoustic characteristics of gas hydrate sediment and to discuss the cause of its formation.We distinguished some abnormal physiognomy and geologic objects that are relevantrelative to gas hydrate in profiles.Protuberance,shallow fault,acoustic blank patch,partial enhanced reflection and acoustic blank zone were discovered in the legible sub-bottom profile.The shallow gassy belt locates under the seabed from 34 to 82m.Contrasting the sub-bottom profile with the data of China’s first gas hydrate expedition,we believed that the gas in the shallow gassy belt came from the decompounding of deeper gas hydrate.Pockmark,seepage,drape and Bottom Simulating Reflector(BSR)were recognized in the single-channel seismic profile.The depth of BSR is slightly deeper than that for the sample of China’s first gas hydrate expedition in the study area.The BSR in the seismic profile might be the bottom of gas hydrate.Based on the time-depth conversion,we plotted out Oligocene,early Miocene epoch,middle Miocene epoch and Pliocene in the seismic profile according to the sediment depth,sediment speed and age of ODP1148 and set up the chronology of the gas hydrate sediment.
引文
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[10]陈忠,颜文,陈木宏,等.南海北部大陆坡冷泉碳酸盐结核的发现—海底天然气渗漏活动的新证据[J].科学通报,2006,51(9):1065-1072.
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[12]葛倩,王家生,向华,等.南海天然气水合物稳定带厚度及资源量估算[J].地球科学:中国地质大学学报,2006,31(2):245-249.
[13]陈林,宋海斌.海底天然气渗漏的地球物理特征及识别方法[J].地球物理学进展,2005,20(4):1067-1073.
[14]陈林,宋海斌.海底天然气渗漏地震探测方法的研究进展[J].天然气工业,2006,26(7):35-40.
[15]王虑远,徐振中,陈世悦,等.天然气水合物的识别标志及研究进展[J].海洋通报,2006,25(2):55-63.
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[20]CHEN D F,HUANG Y Y,YUAN X L,et al.Seep carbonates and preserved methane oxidizing archaea and sulfate reduc-ing bacteria fossils suggest recent gas venting on the seafloorin the Northeastern South China Sea[J].Marine and petro-leum Geology,2005,22(5):613-621.
[21]李家彪,高抒.中国边缘海岩石层结构与动力过程[J].北京:海洋出版社,2003.
[22]李家彪,高抒.中国边缘海海盆演化与资源效应[J].北京:海洋出版社,2004.
[23]祝有海,张光学,卢振权,等.南海天然气水合物成矿条件与找矿前景[J].石油学报,2001,22(5):6-11.
[24]吴时国,姚根顺,董冬冬,等.南海北部陆坡大型气田区天然气水合物的成藏地质构造特征[J].石油学报,2008,29(3):324-328.
[25]李守军,陶春辉,初凤友,等.浅地层剖面在富钴结壳调查研究中的应用[J].海洋技术,2007,26(1):54-57.
[26]ZHANG H,YANG S,WU N,et al.GMGS-1 science team:China’s first gas hydrate expedition successful[J].MethaneHydrate Newsletter:Fire in the Ice,2007,Spring/Summerissue:1.
[27]Guangzhou Marine Geological Survey.Deepwater Gas Hy-drate Investigation,Shenhu Survey Area,South China Sea,Off Shore China(Factual Field Report)[R].Guangzhou:Guangzhou Marine Geological Survey,2007.
[28]倪玉根,郑玉龙,李守军.南海神狐海域上陆坡区典型浅地层剖面的初步解释[J].海洋学研究,2009,27(1):30-36.
[29]李前裕,郑洪波,钟广法,等.南海晚渐新世滑塌沉积指示的地质构造事件[J].地球科学:中国地质大学学报,2005,30(1):19-24.
[30]邵磊,李献华,汪品先,等.南海渐新世以来构造演化的沉积记录——ODP1148站深海沉积物中的证据[J].地球科学进展,2004,19(4):539-544.
[31]唐松,邵磊,赵泉鸿.南海渐新世以来粘土矿物的演变特征及意义[J].沉积学报,2004,22(2):337-342.
[32]房殿勇,王汝建,邵磊,等.南海ODP1148站深海相渐新统硅质成岩作用[J].海洋地质与第四纪地质,2002,22(2):75-79.
[33]董冬冬,吴时国,张功成,等.南海北部深水盆地的裂陷过程及裂陷期延迟机制探讨[J].科学通报,2008,53(19):2342-2351.
[34]李学杰.南海北部陆坡水合物初步研究:ODP钻孔证据[J].南海地质研究,2004:16-28.
[35]田军,汪品先,成鑫荣,等.南海ODP1148站中中新世12—18Ma天文调谐的年代标尺[J].地球科学:中国地质大学学报,2005,30(5):513-518.
[36]陈晓良,赵泉鸿,剪知.南海北部ODP1148站中新世以来的碳酸盐含量变化及其古环境意义[J].海洋地质与第四纪地质,2002,22(2):69-74.
[2]吴能友,张海启,杨胜雄,等.南海神狐海域天然气水合物成藏系统初探[J].天然气工业,2007,27(9):1-7.
[3]陆敬安,杨胜雄,吴能友,等.南海神狐海域天然气水合物地球物理测井评价[J].现代地质,2008,22(3):447-451.
[4]蒋少涌,杨涛,薛紫晨,等.南海北部海区海底沉积物中孔隙中的Cl-和SO42-浓度异常特征及其对天然气水合物的指示意义[J].现代地质,2005,19(1):45-54.
[5]王宏斌,张光学,杨木壮,等.南海陆坡天然气水合物成藏的构造环境[J].海洋地质与第四纪地质,2003,23(1):81-86.
[6]何廉声.多旋回的板块构造运动与南海新生代构造[J].南海地质研究,1988,1:98-108.
[7]吕文正.南海中央海盆条带磁异常特征及构造演化[J].海洋学报,1987,9(1):69-78.
[8]姚伯初.南海海盆新生代的构造演化史[J].海洋地质与第四纪地质,1996,16(2):1-13.
[9]BRIAIS A,PATRIA T P,TAPPONNIER P.Updated inter-pretation of magnetic anomlies and seafloor spreading stagesin the South China Sea:implications for the Tertiary tecton-ics of Southeast Asia[J].Journal of Geophysical Research,1993,98(B4):6299-6328.
[10]陈忠,颜文,陈木宏,等.南海北部大陆坡冷泉碳酸盐结核的发现—海底天然气渗漏活动的新证据[J].科学通报,2006,51(9):1065-1072.
[11]阎贫,刘昭蜀,姜绍仁.南海北部地壳的深地震地质结构探测[J].海洋地质与第四纪地质,1997,17(2):21-27.
[12]葛倩,王家生,向华,等.南海天然气水合物稳定带厚度及资源量估算[J].地球科学:中国地质大学学报,2006,31(2):245-249.
[13]陈林,宋海斌.海底天然气渗漏的地球物理特征及识别方法[J].地球物理学进展,2005,20(4):1067-1073.
[14]陈林,宋海斌.海底天然气渗漏地震探测方法的研究进展[J].天然气工业,2006,26(7):35-40.
[15]王虑远,徐振中,陈世悦,等.天然气水合物的识别标志及研究进展[J].海洋通报,2006,25(2):55-63.
[16]徐华宁,郑晓东,张光学.南中国海存在天然气水合物的地球物理证据[J].地质科技情报,2006,25(2):60-63.
[17]钱建中,曾久岭.地震剖面上的天然气水合物识别方法[J].海洋石油,2002,3:54-59
[18]沙志彬,杨木壮,梁劲,等.南海北部陆坡海底异常地貌特征与天然气水合物的关系[J].南海地质研究,2002,00:29-34.
[19]XIE X,LI S,HE H,et al.Seismic evidence for fluid migra-tion pathways from an overpressured system in the SouthChina Sea[J].Geofluids,2003,3(4):245-253.
[20]CHEN D F,HUANG Y Y,YUAN X L,et al.Seep carbonates and preserved methane oxidizing archaea and sulfate reduc-ing bacteria fossils suggest recent gas venting on the seafloorin the Northeastern South China Sea[J].Marine and petro-leum Geology,2005,22(5):613-621.
[21]李家彪,高抒.中国边缘海岩石层结构与动力过程[J].北京:海洋出版社,2003.
[22]李家彪,高抒.中国边缘海海盆演化与资源效应[J].北京:海洋出版社,2004.
[23]祝有海,张光学,卢振权,等.南海天然气水合物成矿条件与找矿前景[J].石油学报,2001,22(5):6-11.
[24]吴时国,姚根顺,董冬冬,等.南海北部陆坡大型气田区天然气水合物的成藏地质构造特征[J].石油学报,2008,29(3):324-328.
[25]李守军,陶春辉,初凤友,等.浅地层剖面在富钴结壳调查研究中的应用[J].海洋技术,2007,26(1):54-57.
[26]ZHANG H,YANG S,WU N,et al.GMGS-1 science team:China’s first gas hydrate expedition successful[J].MethaneHydrate Newsletter:Fire in the Ice,2007,Spring/Summerissue:1.
[27]Guangzhou Marine Geological Survey.Deepwater Gas Hy-drate Investigation,Shenhu Survey Area,South China Sea,Off Shore China(Factual Field Report)[R].Guangzhou:Guangzhou Marine Geological Survey,2007.
[28]倪玉根,郑玉龙,李守军.南海神狐海域上陆坡区典型浅地层剖面的初步解释[J].海洋学研究,2009,27(1):30-36.
[29]李前裕,郑洪波,钟广法,等.南海晚渐新世滑塌沉积指示的地质构造事件[J].地球科学:中国地质大学学报,2005,30(1):19-24.
[30]邵磊,李献华,汪品先,等.南海渐新世以来构造演化的沉积记录——ODP1148站深海沉积物中的证据[J].地球科学进展,2004,19(4):539-544.
[31]唐松,邵磊,赵泉鸿.南海渐新世以来粘土矿物的演变特征及意义[J].沉积学报,2004,22(2):337-342.
[32]房殿勇,王汝建,邵磊,等.南海ODP1148站深海相渐新统硅质成岩作用[J].海洋地质与第四纪地质,2002,22(2):75-79.
[33]董冬冬,吴时国,张功成,等.南海北部深水盆地的裂陷过程及裂陷期延迟机制探讨[J].科学通报,2008,53(19):2342-2351.
[34]李学杰.南海北部陆坡水合物初步研究:ODP钻孔证据[J].南海地质研究,2004:16-28.
[35]田军,汪品先,成鑫荣,等.南海ODP1148站中中新世12—18Ma天文调谐的年代标尺[J].地球科学:中国地质大学学报,2005,30(5):513-518.
[36]陈晓良,赵泉鸿,剪知.南海北部ODP1148站中新世以来的碳酸盐含量变化及其古环境意义[J].海洋地质与第四纪地质,2002,22(2):69-74.
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