冲绳海槽西侧陆坡及其邻区天然气水合物成藏构造特征
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摘要
为了解特殊地质体与天然气水合物成藏构造特征之间的关系,作者以冲绳海槽西侧陆坡和槽底为例,利用地震资料和地球化学方法对该地区上新世和第四纪沉积物厚度、有机碳含量和断裂系统进行了分析。研究表明,在冲绳海槽西侧及槽底都发育了较厚的上新统和第四系沉积层,上新统厚度约为1000—1500m,第四系厚约为1000—3500m,其中海槽南段存在巨厚的第四系,而且冲绳海槽西侧陆坡沉积物中有机质含量高达0.75%—1.25%,并且沉积速率高达10—40cm/ka,有利于有机质的保存和转化。陆坡发育有与海槽走向一致的NE-SW向断裂系统,以及横切海槽的一系列NW-SE向水平错动扭性断裂系统,其中NE-SW向断层在海槽南段方向变为NEE-SWW,这些断裂系统为烃类气(流)体的运移创造了有利条件。因此,在冲绳海槽西侧陆坡发育的海底峡谷、滑塌体、断块隆脊、泥底辟等特殊地质体与天然气水合物的形成密切相关。
As a special case,the relationship between special geologic structures and hydrate formation the west slope of Okinawa Trough and the trough floor were studied. The thickness of sedimentary deposit of the Pliocene and Quaternary,the organic carbon content and the fault system were studied based on seismic and geo-chemical data. The results show that the sedimentation rate of the study area was high between 10—40 cm/ka,as the Pliocene was 1000—1500 m thick;and the Quaternary was 1000—3500 m thick in the southern Okinawa Trough. The west slope of the trough and the adjacent area were abundant in organic matter of which organic carbon content occupied 0.75%—1.25%. The high sedimentation rate and great thickness should be favorable for organic matter burial and transformation. On the other hand,faults in NE-SW parallel to the trough strike crosscut frequently those in NW-SE direction,of which those in NE-SW changed into NEE-SWW in the south part of the trough. These faults provided advantageous condition for gas hydrate accumulation. Therefore,there are several kinds of structures related to the gas hydrate presence in the study area,such as submarine canyons,slides and slumps,mud diapirs and faulted block ridges.
As a special case,the relationship between special geologic structures and hydrate formation the west slope of Okinawa Trough and the trough floor were studied. The thickness of sedimentary deposit of the Pliocene and Quaternary,the organic carbon content and the fault system were studied based on seismic and geo-chemical data. The results show that the sedimentation rate of the study area was high between 10—40 cm/ka,as the Pliocene was 1000—1500 m thick;and the Quaternary was 1000—3500 m thick in the southern Okinawa Trough. The west slope of the trough and the adjacent area were abundant in organic matter of which organic carbon content occupied 0.75%—1.25%. The high sedimentation rate and great thickness should be favorable for organic matter burial and transformation. On the other hand,faults in NE-SW parallel to the trough strike crosscut frequently those in NW-SE direction,of which those in NE-SW changed into NEE-SWW in the south part of the trough. These faults provided advantageous condition for gas hydrate accumulation. Therefore,there are several kinds of structures related to the gas hydrate presence in the study area,such as submarine canyons,slides and slumps,mud diapirs and faulted block ridges.
引文
丁巍伟,陈汉林,王渝民等,2006.台湾增生楔天然气水合物的地震特征.海洋与湖沼,37(1):90—96
方银霞,黎明碧,金翔龙等,2003.东海冲绳海槽天然气水合物的形成条件.科技通报,19(1):1—5
王宏斌,张光学,杨木壮等,2003.南海陆坡天然气水合物成藏的构造环境.海洋地质与第四纪地质,23(1):81—86
王家林,吴健生,陈冰,1997.珠江口盆地和东海陆架盆地基底结构的综合地球物理研究.上海:同济大学出版社,94—95
刘忠臣,陈义兰,丁继胜等,2003.东海海底地形分区特征和成因研究.海洋科学进展,21(2):160—173
刘保华,李西双,赵月霞等,2005.冲绳海槽西部陆坡碎屑沉积物的搬运方式:滑塌和重力流.海洋与湖沼,36(1):1—9
刘建华,林长松,高金耀等,2005.冲绳海槽南段基底组成分析.海洋与湖沼,36(3):261—267
李乃胜,1988.冲绳海槽断裂构造的研究.海洋与湖沼,19(4):347—358
李培英,王永吉,刘振夏,1999.冲绳海槽年代地层与沉积速率.中国科学(D辑),29(1):50—56
李巍然,杨作升,王琦等,2001.冲绳海槽陆源碎屑峡谷通道搬运与海底扇沉积.海洋与湖沼,32(4):371—380
金翔龙,喻普之,1987.冲绳海槽的构造特征与演化.中国科学(B辑),1:197—203
唐勇,金翔龙,方银霞等,2003.冲绳海槽天然气水合物BSR的地震研究.海洋学报,25(4):59—65
高金满,李国胜,孙家淞等,1987.冲绳海槽的地形地貌特征.海洋地质与第四纪,7(1):51—60
龚建明,杨文达,卢振权等,2001.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,7(7):20—23
喻普之,李乃胜,1992.东海地壳热流.北京:海洋出版社,16
BernéS,Vagner P,Guichare,F et al,2002.Pleistocene forced regressions and tidal sand ridges in the East China Sea.Marine Geology,188:293—315
Bouriak S,Vanneste M,Saoutkine A,2000.Inferred gas hydrates and clay diapirs near the Storegga Slide on theSouthern edge of the V?ring Plateau,offshore Norway.Marine Geology,163:125—148
Ginsburg G D,Milkov A V,Slolviev V A et al,1999.Gas hydrate accumulation at Haakon Mosby mud volcano.Geo-Mar Lett,19:57—67
Letouzey J,Kimura M,1986.The Okinawa Trough:genesis of a back-arc basin developing along a continental margin.Tectonophysics,125:209—230
Kong F C,Lawver A L,Lee T Y,2000.Evolution of the southern Taiwan-Sinzi Folded Zone and opening of the southern Okinawa Trough.Journal of Asian Earth Sci-ence,18:325—341
Lüdmann T,Wong H K,2003.Characteristics of gas hydrate occurrences associated with mud diapirism and gas es-cape structures in the northewestern Sea of Okhotsk.Marine Geology,201:269—286
Milkov A V,2000.Worldwide distribution of submarine mud volcanoes and associated gas hydrates.Marine Geology,167:29—42
Milkov A V,Sassen R,2000.Thickness of the gas hydrate stability zone,Gulf of Mexico continental slope.Ma-rine&Petroleum Geology,17:981—991
Pierre C,Jean-Paul C,Siegfried J L et al,2002.Slope insta-bilities and gravity processes in fluid migration and tectonically active environment in the eastern Nankai accretionary wedge(KAIKO-Tokai’96cruise).Marine Geology,187:193—202
Yin P,BernéS,Vagner P et al,2003.Mud volcanoes at the shelf margin of the East China Sea.Marine Geology,194:135—149
方银霞,黎明碧,金翔龙等,2003.东海冲绳海槽天然气水合物的形成条件.科技通报,19(1):1—5
王宏斌,张光学,杨木壮等,2003.南海陆坡天然气水合物成藏的构造环境.海洋地质与第四纪地质,23(1):81—86
王家林,吴健生,陈冰,1997.珠江口盆地和东海陆架盆地基底结构的综合地球物理研究.上海:同济大学出版社,94—95
刘忠臣,陈义兰,丁继胜等,2003.东海海底地形分区特征和成因研究.海洋科学进展,21(2):160—173
刘保华,李西双,赵月霞等,2005.冲绳海槽西部陆坡碎屑沉积物的搬运方式:滑塌和重力流.海洋与湖沼,36(1):1—9
刘建华,林长松,高金耀等,2005.冲绳海槽南段基底组成分析.海洋与湖沼,36(3):261—267
李乃胜,1988.冲绳海槽断裂构造的研究.海洋与湖沼,19(4):347—358
李培英,王永吉,刘振夏,1999.冲绳海槽年代地层与沉积速率.中国科学(D辑),29(1):50—56
李巍然,杨作升,王琦等,2001.冲绳海槽陆源碎屑峡谷通道搬运与海底扇沉积.海洋与湖沼,32(4):371—380
金翔龙,喻普之,1987.冲绳海槽的构造特征与演化.中国科学(B辑),1:197—203
唐勇,金翔龙,方银霞等,2003.冲绳海槽天然气水合物BSR的地震研究.海洋学报,25(4):59—65
高金满,李国胜,孙家淞等,1987.冲绳海槽的地形地貌特征.海洋地质与第四纪,7(1):51—60
龚建明,杨文达,卢振权等,2001.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,7(7):20—23
喻普之,李乃胜,1992.东海地壳热流.北京:海洋出版社,16
BernéS,Vagner P,Guichare,F et al,2002.Pleistocene forced regressions and tidal sand ridges in the East China Sea.Marine Geology,188:293—315
Bouriak S,Vanneste M,Saoutkine A,2000.Inferred gas hydrates and clay diapirs near the Storegga Slide on theSouthern edge of the V?ring Plateau,offshore Norway.Marine Geology,163:125—148
Ginsburg G D,Milkov A V,Slolviev V A et al,1999.Gas hydrate accumulation at Haakon Mosby mud volcano.Geo-Mar Lett,19:57—67
Letouzey J,Kimura M,1986.The Okinawa Trough:genesis of a back-arc basin developing along a continental margin.Tectonophysics,125:209—230
Kong F C,Lawver A L,Lee T Y,2000.Evolution of the southern Taiwan-Sinzi Folded Zone and opening of the southern Okinawa Trough.Journal of Asian Earth Sci-ence,18:325—341
Lüdmann T,Wong H K,2003.Characteristics of gas hydrate occurrences associated with mud diapirism and gas es-cape structures in the northewestern Sea of Okhotsk.Marine Geology,201:269—286
Milkov A V,2000.Worldwide distribution of submarine mud volcanoes and associated gas hydrates.Marine Geology,167:29—42
Milkov A V,Sassen R,2000.Thickness of the gas hydrate stability zone,Gulf of Mexico continental slope.Ma-rine&Petroleum Geology,17:981—991
Pierre C,Jean-Paul C,Siegfried J L et al,2002.Slope insta-bilities and gravity processes in fluid migration and tectonically active environment in the eastern Nankai accretionary wedge(KAIKO-Tokai’96cruise).Marine Geology,187:193—202
Yin P,BernéS,Vagner P et al,2003.Mud volcanoes at the shelf margin of the East China Sea.Marine Geology,194:135—149
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