跨南海西南次海盆OBS、多道地震与重力联合调查
|
摘要
对跨南海西南次海盆及两侧陆缘的一条1050km长的、包括海底地震(OBS)、长排列多道地震和重磁在内的综合地球物理探测剖面(CFT)进行了构造成像和研究。在多道地震成像基础上建立了CFT剖面初始速度模型,进而通过初至波层析成像方法反演了CFT剖面的速度结构模型,在重力异常资料的约束下建立了CFT剖面的综合地壳结构模型。讨论了沿CFT剖面出现的下地壳高速体、龙门海山的低密度物质等地质问题。结果表明,下地壳高速层在北部陆坡、西南海盆和南部南沙地块均有分布,厚度在0～4km之间,可能与陆缘下地壳物质和地幔物质熔融混合,以及深海盆海底扩张期间构造拉伸导致地幔蛇纹岩化有关。
A 1050-km long comprehensive geophysical profile(CFT) was acquired across the conjugate margins of the southwestern sub-basin of the South China Sea, which includes 49 OBSs, 6-or 8-km long streamer, gravimeter, and magnetometer. Various refined processing procedures were applied to the aforementioned geophysical data; and a joint reflection and refraction seismic travel time inversion was performed to derive a 2-D velocity model of the crustal structure and upper mantle. Based on this new tomographic model and shipboard gravity data, a comprehensive crustal structure model was created. Finally, some interesting issues including High Velocity Layer(HVL) in the base of crust, an anomalous low density seamount(long-men seamount) along the CFT profile are discussed in this paper. HVL are widely distributed under the northern slope, southwestern sub-basin and Nansha block along the CFT profile, with the velocity varying from 7.0 to 7.5 km·s-1, and thickness between 0 and 4 km. HVL in the marginal lower crust might be derived from melting and mixing of lower crust material and mantle material, and HVL in the oceanic crust might have originated from serpentinization by tectonically dominated seafloor spreading.
A 1050-km long comprehensive geophysical profile(CFT) was acquired across the conjugate margins of the southwestern sub-basin of the South China Sea, which includes 49 OBSs, 6-or 8-km long streamer, gravimeter, and magnetometer. Various refined processing procedures were applied to the aforementioned geophysical data; and a joint reflection and refraction seismic travel time inversion was performed to derive a 2-D velocity model of the crustal structure and upper mantle. Based on this new tomographic model and shipboard gravity data, a comprehensive crustal structure model was created. Finally, some interesting issues including High Velocity Layer(HVL) in the base of crust, an anomalous low density seamount(long-men seamount) along the CFT profile are discussed in this paper. HVL are widely distributed under the northern slope, southwestern sub-basin and Nansha block along the CFT profile, with the velocity varying from 7.0 to 7.5 km·s-1, and thickness between 0 and 4 km. HVL in the marginal lower crust might be derived from melting and mixing of lower crust material and mantle material, and HVL in the oceanic crust might have originated from serpentinization by tectonically dominated seafloor spreading.
引文
高金耀,汪俊,邱燕,等,2015.莫霍面深度图1:2 000 000[M]//杨胜雄,邱燕,朱本铎,等.南海地质地球物理图系.天津:中国航海图书出版社.GAO JINYAO,WANG JUN,QIUYAN,et al,2015.1:2000000 map of Moho depth[M]//YANGSHENGXIONG,QIU YAN,ZHU BENDUO,et al,2015.Atlas of geology and geophysics of South China.Tianjin:China Navigation Book Publishing House(in Chinese).
郝天珧,黄松,徐亚,等,2008.南海东北部及邻区深部结构的综合地球物理研究[J].地球物理学报,51(6):1785-1796.HAO TIANYAO,HUANG SONG,XU YA,et al,2008.Comprehensive geophysical research on the deep structure of Northeastern South China Sea[J].Chinese Journal of Geophysics,51(6):1785-1796(in Chinese with English abstract).
郝天珧,徐亚,赵百民,等,2009.南海磁性基底分布特征的地球物理研究[J].地球物理学报,52(11):2763-2774.HAOTIANYAO,XU YA,ZHAO BAIMIN,et al,2009.Geophysical research on distribution features of magnetic basements in the South China Sea[J].Chinese Journal of Geophysics,52(11):2763-2774(in Chinese with English abstract).
李春峰,宋晓晓,2014.国际大洋发现计划IODP349航次[J].上海国土资源,35(2):43-48.LI CHUNFENG,SONGXIAOXIAO,2014.International ocean discovery program(IODP)expedition 349[J].Shanghai Land&Resources,35(2):43-48(in Chinese with English abstract).
吕文正,柯长志,吴声迪,等,1987.南海中央海盆条带磁异常特征及构造演化[J].海洋学报,9(1):69-78(in Chinese).
邱燕,汪俊,黄文凯,等,2016.南海海域地壳结构特征及其构造意义[M]//中国地质调查局,广州海洋地质调查局.南海地质研究.北京:地质出版社:1-32.QIU YAN,WANGJUN,HUANG WENKAI,et al,2016.The crustal structure characteristics and its tectonic significance of South China Sea[M]//China Geological Survey,Guangzhou Marine Geological Survey.Geological research of South China Sea.Beijing:Geological Publishing House:1-32(in Chinese).
吴招才,高金耀,李家彪,等,2011.南海北部磁异常特征及对前新生代构造的指示[J].地球物理学报,54(12):3292-3302.WU ZHAOCAI,GAO JINYAO,LI JIABIAO,et al,2011.The characteristics of magnetic anomalies:implications for Pre-Cenozoic tectonics of the Northern South China Sea[J].Chinese Journal of Geophysics,54(12):3292-3302(in Chinese with English abstract).
吴振利,李家彪,阮爱国,等,2011.南海西北次海盆地壳结构:海底广角地震实验结果[J].中国科学:地球科学,41(10):1463-1476.WU ZHENLI,LI JIABIAO,RUAN AIGUO,et al,2012.Crustal structure of the northwestern sub-basin,South China sea:results from a wide-angle seismic experiment[J].Science China Earth Sciences,55(1):159-172.
阎贫,刘海龄,2002.南海北部陆缘地壳结构探测结果分析[J].热带海洋学报,21(2):1-12.YAN PIN,LIU HAILING,2002.Analysis on deep crust sounding results in northern margin of South China Sea[J].Journal of Tropical Oceanography,21(2):1-12(in Chinese with English abstract).
姚伯初,曾维军,HAYES D E,等,1994.中美合作调研南海地质专报[M].武汉:中国地质大学出版社.YAO BOCHU,ZENG WEIJUN,HAYES D E,et al,1994.The geological memoir of South China sea surveyed jointly by China&USA[M].Wuhan:China University of Geosciences Press(in Chinese).
于俊辉,阎贫,郑红波,等,2017.南海西南次海盆反射莫霍面成像及其地质意义[J].海洋地质与第四纪地质,37(2):75-81.YU JUNHUI,YAN PIN,ZHENG HONGBO,et al,2017.Imaging of reflection Moho in the southwest sub-basin of South China Sea and its geological implications[J].Marine Geology&Quaternary Geology,37(2):75-81(in Chinese with English abstract).
周蒂,王万银,庞雄,等,2006.地球物理资料所揭示的南海东北部中生代俯冲增生带[J].中国科学D辑:地球科学,36(3):209-218.ZHOU DI,WANG WANYIN,PANGXIONG,et al,2006.Mesozoic subduction-accretion zone in Northeastern South China Sea inferred from geophysical interpretations[J].Science in China Series D,49(5):471-482.
BRIAIS A,PATRIAT P,TAPPONNIER P,1993.Updated interpretation of magnetic anomalies and seafloor spreading stages in the South China Sea:implications for the tertiary tectonics of southeast Asia[J].Journal of Geophysical Research,98(B4):6299-6328.
FRYER P,GHARIB J,ROSS K,et al,2006.Variability in serpentinite mudflow mechanisms and sources:ODP drilling results on Mariana forearc seamounts[J].Geochemistry,Geophysics,Geosystems,70(8):Q08014,doi:10.1029/2005GC001201.
KORENAGA J,HOLBROOK W S,KENT G M,et al,2000.Crustal structure of the southeast Greenland margin from joint refraction and reflection seismic tomography[J].Journal of Geophysical Research,105(B9):21591-21614.
MIURA R,NAKAMURA Y,KODA K,et al,2004.“Rootless’’serpentinite seamount on the southern Izu-Bonin forearc:implications for basal erosion at convergent plate margins[J].Geology,32(6):541-544,doi:10.1130/G20319.1.
NISSEN S S,HAYES D E,YAO BOCHU,et al,1995.Gravity,heat flow,and seismic constraints on the processes of crustal extension:Northern margin of the South China Sea[J].Journal of Geophysical Research,100(B11):22447-22483.
PICHOT T,DELESCLUSE M,CHAMOT-ROOKE N,et al,2014.Deep crustal structure of the conjugate margins of the SWSouth China Sea from wide-angle refraction seismic data[J].Marine and Petroleum Geology,58:627-643,doi:10.1016/j.marpetgeo.2013.10.008.
QIU XUELIN,YE SANYU,WU SHIMIN,et al,2001.Crustal structure across the Xisha Trough,northwestern South China Sea[J].Tectonophysics,341(1-4):179-193.
QIU XUELIN,SHI XIAOBIN,YAN PIN,et al,2003.Recent progress of deep seismic experiments and studies of crustal structure in northern South China Sea[J].Progress in Natural Science,13(7):481-488.
WANG YANLIN,WANG JUN,YAN PIN,et al,2017.An anomalous seamount on the southwestern mid-ridge of the South China Sea[J].Acta Geologica Sinica,91(6):2340-2341.
YAN PIN,ZHOU DI,LIU ZHAOSHU,2001.A crustal structure profile across the northern continental margin of the South China Sea[J].Tectonophysics,338(1):1-21.
YU JUNHUI,YAN PIN,WANG YANLIN,et al,2018.Seismic evidence for tectonically dominated seafloor spreading in the Southwest Sub-basin of the South China Sea[J].Geochemistry,Geophysics,Geosystems,19(9):3459-3477.
郝天珧,黄松,徐亚,等,2008.南海东北部及邻区深部结构的综合地球物理研究[J].地球物理学报,51(6):1785-1796.HAO TIANYAO,HUANG SONG,XU YA,et al,2008.Comprehensive geophysical research on the deep structure of Northeastern South China Sea[J].Chinese Journal of Geophysics,51(6):1785-1796(in Chinese with English abstract).
郝天珧,徐亚,赵百民,等,2009.南海磁性基底分布特征的地球物理研究[J].地球物理学报,52(11):2763-2774.HAOTIANYAO,XU YA,ZHAO BAIMIN,et al,2009.Geophysical research on distribution features of magnetic basements in the South China Sea[J].Chinese Journal of Geophysics,52(11):2763-2774(in Chinese with English abstract).
李春峰,宋晓晓,2014.国际大洋发现计划IODP349航次[J].上海国土资源,35(2):43-48.LI CHUNFENG,SONGXIAOXIAO,2014.International ocean discovery program(IODP)expedition 349[J].Shanghai Land&Resources,35(2):43-48(in Chinese with English abstract).
吕文正,柯长志,吴声迪,等,1987.南海中央海盆条带磁异常特征及构造演化[J].海洋学报,9(1):69-78(in Chinese).
邱燕,汪俊,黄文凯,等,2016.南海海域地壳结构特征及其构造意义[M]//中国地质调查局,广州海洋地质调查局.南海地质研究.北京:地质出版社:1-32.QIU YAN,WANGJUN,HUANG WENKAI,et al,2016.The crustal structure characteristics and its tectonic significance of South China Sea[M]//China Geological Survey,Guangzhou Marine Geological Survey.Geological research of South China Sea.Beijing:Geological Publishing House:1-32(in Chinese).
吴招才,高金耀,李家彪,等,2011.南海北部磁异常特征及对前新生代构造的指示[J].地球物理学报,54(12):3292-3302.WU ZHAOCAI,GAO JINYAO,LI JIABIAO,et al,2011.The characteristics of magnetic anomalies:implications for Pre-Cenozoic tectonics of the Northern South China Sea[J].Chinese Journal of Geophysics,54(12):3292-3302(in Chinese with English abstract).
吴振利,李家彪,阮爱国,等,2011.南海西北次海盆地壳结构:海底广角地震实验结果[J].中国科学:地球科学,41(10):1463-1476.WU ZHENLI,LI JIABIAO,RUAN AIGUO,et al,2012.Crustal structure of the northwestern sub-basin,South China sea:results from a wide-angle seismic experiment[J].Science China Earth Sciences,55(1):159-172.
阎贫,刘海龄,2002.南海北部陆缘地壳结构探测结果分析[J].热带海洋学报,21(2):1-12.YAN PIN,LIU HAILING,2002.Analysis on deep crust sounding results in northern margin of South China Sea[J].Journal of Tropical Oceanography,21(2):1-12(in Chinese with English abstract).
姚伯初,曾维军,HAYES D E,等,1994.中美合作调研南海地质专报[M].武汉:中国地质大学出版社.YAO BOCHU,ZENG WEIJUN,HAYES D E,et al,1994.The geological memoir of South China sea surveyed jointly by China&USA[M].Wuhan:China University of Geosciences Press(in Chinese).
于俊辉,阎贫,郑红波,等,2017.南海西南次海盆反射莫霍面成像及其地质意义[J].海洋地质与第四纪地质,37(2):75-81.YU JUNHUI,YAN PIN,ZHENG HONGBO,et al,2017.Imaging of reflection Moho in the southwest sub-basin of South China Sea and its geological implications[J].Marine Geology&Quaternary Geology,37(2):75-81(in Chinese with English abstract).
周蒂,王万银,庞雄,等,2006.地球物理资料所揭示的南海东北部中生代俯冲增生带[J].中国科学D辑:地球科学,36(3):209-218.ZHOU DI,WANG WANYIN,PANGXIONG,et al,2006.Mesozoic subduction-accretion zone in Northeastern South China Sea inferred from geophysical interpretations[J].Science in China Series D,49(5):471-482.
BRIAIS A,PATRIAT P,TAPPONNIER P,1993.Updated interpretation of magnetic anomalies and seafloor spreading stages in the South China Sea:implications for the tertiary tectonics of southeast Asia[J].Journal of Geophysical Research,98(B4):6299-6328.
FRYER P,GHARIB J,ROSS K,et al,2006.Variability in serpentinite mudflow mechanisms and sources:ODP drilling results on Mariana forearc seamounts[J].Geochemistry,Geophysics,Geosystems,70(8):Q08014,doi:10.1029/2005GC001201.
KORENAGA J,HOLBROOK W S,KENT G M,et al,2000.Crustal structure of the southeast Greenland margin from joint refraction and reflection seismic tomography[J].Journal of Geophysical Research,105(B9):21591-21614.
MIURA R,NAKAMURA Y,KODA K,et al,2004.“Rootless’’serpentinite seamount on the southern Izu-Bonin forearc:implications for basal erosion at convergent plate margins[J].Geology,32(6):541-544,doi:10.1130/G20319.1.
NISSEN S S,HAYES D E,YAO BOCHU,et al,1995.Gravity,heat flow,and seismic constraints on the processes of crustal extension:Northern margin of the South China Sea[J].Journal of Geophysical Research,100(B11):22447-22483.
PICHOT T,DELESCLUSE M,CHAMOT-ROOKE N,et al,2014.Deep crustal structure of the conjugate margins of the SWSouth China Sea from wide-angle refraction seismic data[J].Marine and Petroleum Geology,58:627-643,doi:10.1016/j.marpetgeo.2013.10.008.
QIU XUELIN,YE SANYU,WU SHIMIN,et al,2001.Crustal structure across the Xisha Trough,northwestern South China Sea[J].Tectonophysics,341(1-4):179-193.
QIU XUELIN,SHI XIAOBIN,YAN PIN,et al,2003.Recent progress of deep seismic experiments and studies of crustal structure in northern South China Sea[J].Progress in Natural Science,13(7):481-488.
WANG YANLIN,WANG JUN,YAN PIN,et al,2017.An anomalous seamount on the southwestern mid-ridge of the South China Sea[J].Acta Geologica Sinica,91(6):2340-2341.
YAN PIN,ZHOU DI,LIU ZHAOSHU,2001.A crustal structure profile across the northern continental margin of the South China Sea[J].Tectonophysics,338(1):1-21.
YU JUNHUI,YAN PIN,WANG YANLIN,et al,2018.Seismic evidence for tectonically dominated seafloor spreading in the Southwest Sub-basin of the South China Sea[J].Geochemistry,Geophysics,Geosystems,19(9):3459-3477.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |