西南印度洋洋中脊热液A区海底地震仪数据处理初步成果
摘要
在西南印度洋热液活动A区(49°39′E)开展的三维海底地震仪(OBS)探测实验为研究该区域的深部地壳/上地幔结构提供了重要基础,而OBS数据处理是获取研究区三维速度结构的基础环节。文章介绍了此次实验中所用的3种不同类型OBS(国产、法国和德国OBS)的数据处理流程,包括地震数据解编处理、截裁处理和地震信号的可视化处理;并以第2790炮为例分析了3种类型OBS记录数据的波形和频谱特征。结果表明,由于受不同类型OBS的频带、传感器和拾震器等影响,国产与法国OBS都能记录到长周期和短周期噪音,而德国OBS只记录到短周期噪音;但经带通滤波后,3种类型OBS都能够很好地压制噪音,突出有用的气枪信号;对比3种类型OBS(分别以OBS04、OBS08和OBS23为例)沿主测线X1X2的综合记录剖面,发现3种类型OBS都能够记录到多组清晰可靠的P波震相,如直达水波、Pg、PmP和Pn震相,为下一步A区的三维层析成像奠定了坚实数据基础。
Three-dimensional(3D) ocean bottom seismometer(OBS) survey provides a significant foundation for the deep crustal and upper mantle structure of the hydrothermal field(49°39′E)(Area A) in the Southwest Indian Ridge.OBS data processing is the basic step of obtaining the 3D seismic velocity structure.The flow steps for data processing of three types of OBS(domestic,French and Germanic OBS) were firstly introduced,containing the decompilation,cutting and seismic signal visualization.Taking the shot 2790th for example,waveforms and frequency spectrums of three types of OBSs were then analyzed,which were related to frequency band,sensor and seismograph for different OBSs.Domestic and French OBSs recorded long-periodic and short-periodic noises,and Germanic OBS only recorded short-periodic noises.However,air-gun signals were highlighted and noises were suppressed for all the OBSs after using a band-passed filter.Moreover,several seismic phases,e.g.,Pg,PmP and Pn,were clearly revealed in the recorded seismic sections of three types of OBSs(OBS04, OBS08 and OBS23) along the profile X1X2.These phases will provide a strong data base for 3D tomography for studying Area A.
Three-dimensional(3D) ocean bottom seismometer(OBS) survey provides a significant foundation for the deep crustal and upper mantle structure of the hydrothermal field(49°39′E)(Area A) in the Southwest Indian Ridge.OBS data processing is the basic step of obtaining the 3D seismic velocity structure.The flow steps for data processing of three types of OBS(domestic,French and Germanic OBS) were firstly introduced,containing the decompilation,cutting and seismic signal visualization.Taking the shot 2790th for example,waveforms and frequency spectrums of three types of OBSs were then analyzed,which were related to frequency band,sensor and seismograph for different OBSs.Domestic and French OBSs recorded long-periodic and short-periodic noises,and Germanic OBS only recorded short-periodic noises.However,air-gun signals were highlighted and noises were suppressed for all the OBSs after using a band-passed filter.Moreover,several seismic phases,e.g.,Pg,PmP and Pn,were clearly revealed in the recorded seismic sections of three types of OBSs(OBS04, OBS08 and OBS23) along the profile X1X2.These phases will provide a strong data base for 3D tomography for studying Area A.
引文
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[12]SAUTER D.,CANNAT M.,MEYZEN C.,et al.Propagationof a melting anomaly along the ultraslow Southwest IndianRidge between 46°E and 52°20'E:interaction with the Crozethotspot?[J].Geophysical Journal International,2009,179(2):687-699.
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[14]MULLER M R,ROBINSON C J,MINSHULL T A,et al.Thin crust beneath borehole 735B at the Southwest IndianRidge?[J].Earth and Planetary Science Letters,1997,148:93-107.
[15]MINSHULL T A,MULLER M R,WHITE R S.Crustalstructure of the Southwest Indian Ridge at 66°E:Seismicconstraints[J].Geophysical Journal International,2006,166:135-147.
[16]GERMAN C R,BAKER E T,MEVEL C,et al.Hydrothermal activity along the southwest Indian ridge[J].Nature,1998,395(6701):490-493.
[17]TAO C H,LIN J,GUO S,et al.Discovery of the first activehydrothermal vent field at the ultraslow spreading SouthwestIndian Ridge[J].InterRidge News,2007,16:25-26.
[18]GEORGEN J E,KURZ M D,DICK H J B,et al.LowHe-3/He-4 ratios in basalt glasses from the westernSouthwest Indian Ridge(10 degrees-24 degrees E)[J].Earthand Planetary Science Letters,2003,206(3-4):509-528.
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[21]ZHU J,LIN J,CHEN Y S,et al.A reduced crustalmagnetization zone near the first observed activehydrothermal vent field on the Southwest Indian Ridge[J].Geophysical Research Letters,2010,37:1-5.
[22]THOMPSON G,HUMPHRIS S E,SCHROEDER B,et al.Active vents and massive sulfides at 26°N(TAG)and 23°N(Snakepit)on the Mid-Atlantic Ridge[J].Canadian Mineral,1988,26:697-711.
[23]TIVEY M K,HUMPHRIS S E,THOMPSON G,et al.Deducing patterns of fluid flow and mixing within the activeTAG mound using mineralogical and geochemical data[J].Journal of Geophysical Research,1995,100(12):527-556.
[24]赵明辉,丘学林,李家彪,等.慢速、超慢速扩张洋中脊三维地震结构研究进展与展望[J].热带海洋学报,2010,29(6):1-7.
[25]丘学林,施小斌,阎贫,等.南海北部地壳结构的深地震探测和研究进展[J].自然科学进展,2003,13(3):231-236.
[26]赵明辉,丘学林,夏少红,等.大容量气枪震源及其波形特征[J].地球物理学报,2008,51(2):558-565.
[27]敖威,赵明辉,丘学林,等.西南印度洋中脊三维地震探测中炮点与海底地震仪的位置校正[J].地球物理学报,2010,53(12):2982-2991.
[28]BARRY K M,CAVERS D A,KNEALE C W.Recommended standards for digital tape formats[J].Geophysics,40(2):344-352.
[29]FORSYTH D,DETRICK B.Ocean Mantle DynamicsScience Plan[R].Woods Hole Oceanographic Institution,2000:l-36.
[30]阮爱国,李家彪,冯占英,等.海底地震仪及其国内外发展现状[J].东海海洋,2004,22(2):19-27.
[31]游庆瑜,刘福田,冉崇荣,等.高频微功耗海底地震仪研制[J].地球物理学进展,2003,18(1):173-176.
[32]邵安民,张玉云,赵风文.海底地震数据记录器[J].地球物理学报,2003,46(2):224-228.
[33]王嘹亮,张志荣,阎贫,等.潮汕坳陷地壳结构探测初步成果[J].南海地质研究,2003,15:62-67.
[34]阮爱国,李家彪,陈永顺,等.国产I-4C型OBS在西南印度洋中脊的试验[J].地球物理学报,2010,53(4):1015-1018.
[35]王芳.国产海底地震仪产业化之路——海底流动地震观测台阵研发记[J].中国发明与专利,2011,4:105-107.
[36]李湘云,吴振利,薛彬,等.SEDIS IV型短周期自浮式海底地震仪及应用体会[J].热带海洋学报,2007,26(5):735-39.
[37]WILLIAM C T,JOSEPH E T.SAC-Seismic Analysis CodeUSERS MANUAL[M].Lawrence Livermore NationalLaboratory,Livermore,CA,1991:1-153.
[38]COHEN J K,STOCKWELL J W.The SU user’s manual[R].Colorado School of Mines,1995:1-40.
[39]赵明辉,丘学林,夏戡原,等.南海东北部海陆联测地震数据处理及初步结果[J].热带海洋学报,2004,23(1):58-63.
[40]敖威,赵明辉,阮爱国,等.利用海底地震仪数据分析台风对海底环境噪音的影响[J].热带海洋学报,2009,28(6):61-67.
[41]刘宏扬,牛雄伟,阮爱国,等.海底地震仪实测信号特性分析[J].热带海洋学报,2012,31(3):90-96.
[2]MENDEL V,SAUTER D,PARSON L,et al.Segmentationand morphotectonic variations along a super slow-spreadingcenter:the Southwest Indian Ridge(57°E-70°E)[J].MarineGeophysical Researches,1997,19:505-533.
[3]CANNAT M,ROMMEVAUX-JESTIN C,SAUTER D,et al.Formation of the axial relief at the very slow spreadingSouthwest Indian Ridge(49°to 69°E)[J].Journal ofGeophysical Research,1999,104:22825-22843.
[4]CANNAT M,SAUTER D,MENDEL V,et al.Modes ofseafloor generation at a melt-poor ultraslow-spreading ridge[J].Geology,2006,34(7):605-608.
[5]SAUTER D,PATRIAT P,ROMMEVAUX-JESTIN C,et al.The Southwest Indian Ridge between 49°15′E and 57°E:Focused accretion and magma redistribution[J].Earth andPlanetary Science Letter,2001,192:303–317.
[6]PATRIAT P,SAUTER D,MUNSCHY M,et al.A survey ofthe Southwest Indian Ridge axis between Atlantis II fracturezone and the Indian Ocean triple junction:Regional settingand large scale segmentation[J].Marine GeophysicalResearches,1997,19:457-480.
[7]MENDEL V,SAUTER D,ROMMEVAUX-JESTIN C,et al.Magmato-tectonic cyclicity at the ultra-slow spreadingSouthwest Indian Ridge:Evidence from variations of axialvolcanic ridge morphology and abyssal hills pattern[J].Geochemistry Geophysics Geosystems,2003,4(5):1-23.
[8]GOMEZ O,BRIAIS A,SAUTER D,et al.Tectonics at theaxis of the very slow spreading Southwest Indian Ridge:Insights from TOBI side-scan sonar imagery[J].Geochemistry Geophysics Geosystems,2006,7:1-24.
[9]ROMMEVAUX-JESTIN C,DEPLUS C,PATRIAT P.Mantle Bouguer Anomaly along an ultra slow spreadingridge:implications for accretionary process and comparisonwith results from central Mid-Atlantic Ridge[J].MarineGeophysical Researches,1997,19:481-503.
[10]GRINDLAY N R,MADSEN J A,ROMMEVAUX-JESTINC,et al.A different pattern of ridge segmentation and mantleBouguer gravity anomalies along the ultra-slow spreadingSouthwest Indian Ridge(15°30E-70°E)[J].Earth andPlanetary Science Letters,1998,161:243-253.
[11]GEORGEN J E,LIN J,DICK H J B.Evidence from gravityanomalies for interactions of the Marion and Bouvet hotspotswith the Southwest Indian Ridge:effects of transform offsets[J].Earth and Planetary Science Letters,2001,187:283-300.
[12]SAUTER D.,CANNAT M.,MEYZEN C.,et al.Propagationof a melting anomaly along the ultraslow Southwest IndianRidge between 46°E and 52°20'E:interaction with the Crozethotspot?[J].Geophysical Journal International,2009,179(2):687-699.
[13]HOSFORD A,TIVEY M,MATSUMOTO T,et al.Crustalmagnetization and accretion at the Southwest Indian Ridgenear the Atlantis II fracture zone,0-25 Ma[J].Journal ofGeophysical Research,2003,108:1-23.
[14]MULLER M R,ROBINSON C J,MINSHULL T A,et al.Thin crust beneath borehole 735B at the Southwest IndianRidge?[J].Earth and Planetary Science Letters,1997,148:93-107.
[15]MINSHULL T A,MULLER M R,WHITE R S.Crustalstructure of the Southwest Indian Ridge at 66°E:Seismicconstraints[J].Geophysical Journal International,2006,166:135-147.
[16]GERMAN C R,BAKER E T,MEVEL C,et al.Hydrothermal activity along the southwest Indian ridge[J].Nature,1998,395(6701):490-493.
[17]TAO C H,LIN J,GUO S,et al.Discovery of the first activehydrothermal vent field at the ultraslow spreading SouthwestIndian Ridge[J].InterRidge News,2007,16:25-26.
[18]GEORGEN J E,KURZ M D,DICK H J B,et al.LowHe-3/He-4 ratios in basalt glasses from the westernSouthwest Indian Ridge(10 degrees-24 degrees E)[J].Earthand Planetary Science Letters,2003,206(3-4):509-528.
[19]COOGAN L A,THOMPSON G M,MACLEOD C J,et al.Acombined basalt and peridotite perspective on 14 millionyears of melt generation at the Atlantis Bank segment of theSouthwest Indian Ridge:evidence for temporal changes inmantle dynamics?[J].Chemical Geology,2004,207(1-2):13-30.
[20]LIN J,ZHANG C.The first collaborative China-International cruises to investigate Mid-Ocean ridgehydrothermal vents[J].Ridge Crest News,2006,15:33-34.
[21]ZHU J,LIN J,CHEN Y S,et al.A reduced crustalmagnetization zone near the first observed activehydrothermal vent field on the Southwest Indian Ridge[J].Geophysical Research Letters,2010,37:1-5.
[22]THOMPSON G,HUMPHRIS S E,SCHROEDER B,et al.Active vents and massive sulfides at 26°N(TAG)and 23°N(Snakepit)on the Mid-Atlantic Ridge[J].Canadian Mineral,1988,26:697-711.
[23]TIVEY M K,HUMPHRIS S E,THOMPSON G,et al.Deducing patterns of fluid flow and mixing within the activeTAG mound using mineralogical and geochemical data[J].Journal of Geophysical Research,1995,100(12):527-556.
[24]赵明辉,丘学林,李家彪,等.慢速、超慢速扩张洋中脊三维地震结构研究进展与展望[J].热带海洋学报,2010,29(6):1-7.
[25]丘学林,施小斌,阎贫,等.南海北部地壳结构的深地震探测和研究进展[J].自然科学进展,2003,13(3):231-236.
[26]赵明辉,丘学林,夏少红,等.大容量气枪震源及其波形特征[J].地球物理学报,2008,51(2):558-565.
[27]敖威,赵明辉,丘学林,等.西南印度洋中脊三维地震探测中炮点与海底地震仪的位置校正[J].地球物理学报,2010,53(12):2982-2991.
[28]BARRY K M,CAVERS D A,KNEALE C W.Recommended standards for digital tape formats[J].Geophysics,40(2):344-352.
[29]FORSYTH D,DETRICK B.Ocean Mantle DynamicsScience Plan[R].Woods Hole Oceanographic Institution,2000:l-36.
[30]阮爱国,李家彪,冯占英,等.海底地震仪及其国内外发展现状[J].东海海洋,2004,22(2):19-27.
[31]游庆瑜,刘福田,冉崇荣,等.高频微功耗海底地震仪研制[J].地球物理学进展,2003,18(1):173-176.
[32]邵安民,张玉云,赵风文.海底地震数据记录器[J].地球物理学报,2003,46(2):224-228.
[33]王嘹亮,张志荣,阎贫,等.潮汕坳陷地壳结构探测初步成果[J].南海地质研究,2003,15:62-67.
[34]阮爱国,李家彪,陈永顺,等.国产I-4C型OBS在西南印度洋中脊的试验[J].地球物理学报,2010,53(4):1015-1018.
[35]王芳.国产海底地震仪产业化之路——海底流动地震观测台阵研发记[J].中国发明与专利,2011,4:105-107.
[36]李湘云,吴振利,薛彬,等.SEDIS IV型短周期自浮式海底地震仪及应用体会[J].热带海洋学报,2007,26(5):735-39.
[37]WILLIAM C T,JOSEPH E T.SAC-Seismic Analysis CodeUSERS MANUAL[M].Lawrence Livermore NationalLaboratory,Livermore,CA,1991:1-153.
[38]COHEN J K,STOCKWELL J W.The SU user’s manual[R].Colorado School of Mines,1995:1-40.
[39]赵明辉,丘学林,夏戡原,等.南海东北部海陆联测地震数据处理及初步结果[J].热带海洋学报,2004,23(1):58-63.
[40]敖威,赵明辉,阮爱国,等.利用海底地震仪数据分析台风对海底环境噪音的影响[J].热带海洋学报,2009,28(6):61-67.
[41]刘宏扬,牛雄伟,阮爱国,等.海底地震仪实测信号特性分析[J].热带海洋学报,2012,31(3):90-96.
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