冲绳海槽——弧后背景下大陆张裂的最高阶段
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摘要
高热流值、强地震活动、火山活动、张性断层作用以及快速沉降等特征表明冲绳海槽的演化已经达到了大陆张裂的最高阶段。根据地震折射和重力资料的计算表明冲绳海槽底下存在低密度的异常地幔 ,冲绳海槽的莫霍面介于 15 .4～ 2 3.8km之间。在我们提出的边缘海盆地演化旋回中 ,冲绳海槽处于胚胎期 ,即处在大陆张裂的最高阶段和弧后海底扩张的过渡阶段。冲绳海槽也可视为是威尔逊旋回中连接东非裂谷和红海阶段的一个重要的中间环节
Characteristics of the Okinawa Trough such as high heat flow values,intensive earthquake activities,volcanic activities,extensional faulting and rapid subsidence have indicated that the evolution of the trough has reached the highest stage of continental tension rifting.Calculations from seismic refraction and gravitational data show that anomalous mantle of low density exist beneath the Okinawa Trough and that Moho in the trough lies between 15 4 km and 23 8 km in depth.In our proposed evolutional cycles for marginal sea basins,the Okinawa Trough is in the embryonic stage,that means it is in the highest stage of continental tension rifting and in the transitional stage of back arc seafloor spreading.The Okinawa Trough can also be considered as an important link between East African Rift and Red Sea stage in the Wilson Cycle.
Characteristics of the Okinawa Trough such as high heat flow values,intensive earthquake activities,volcanic activities,extensional faulting and rapid subsidence have indicated that the evolution of the trough has reached the highest stage of continental tension rifting.Calculations from seismic refraction and gravitational data show that anomalous mantle of low density exist beneath the Okinawa Trough and that Moho in the trough lies between 15 4 km and 23 8 km in depth.In our proposed evolutional cycles for marginal sea basins,the Okinawa Trough is in the embryonic stage,that means it is in the highest stage of continental tension rifting and in the transitional stage of back arc seafloor spreading.The Okinawa Trough can also be considered as an important link between East African Rift and Red Sea stage in the Wilson Cycle.
引文
[1] Kimura M.Back-arc rifting in the Okinawa Trough[J] .Marineand Petroleum Geology,1985 ,2 :2 2 2 -2 40 .
[2 ] Letouzey J,Kimura M.The Okinawa Trough:genesis of aback-arc basin developing along a continental margin[J] .Tectonophysics,1986,12 5 :2 0 9-2 3 0 .
[3 ] Hirata N,Kinoshita H,Katao H,et al.Report on DEL P 1988cruises in the Okinawa Trough part3 :Crustal structure of thesouthern Okinawa Trough[J] .Bulletin of the Earthquake Re-search Institute,University of Tokyo,1991,66:3 7-70 .
[4] 李乃胜 .冲绳海槽海底热流研究 [J] .海洋学报 ,1992 ,14 (4) :87-93 .
[5 ] Kinoshita M,Yamano M,Kasumi Y,et al.Report on DELP1988cruises in the Okinawa Trough part 8:Heat flow m ea-surem ents[J] .Bulletin of the Earthquake Research Institute,University of Tokyo,1991,66:2 11-2 2 8.
[6] Yamano M,Uyeda S,Foucher J P,Sibuet J C.Heat flowanomaly in the middle Okinawa Trough [J] .Tectonophysics,1989,15 9:3 0 7-3 18.
[7] Sato T,Koresawa S,Shioyu Y,Kusano F ,Uechi S,NagaokaO,Kasahara J.Microseismicity of back-arc rifting in the mid-dle Okinawa Trough[J] .Geophs.Res.L etts.,1994,2 1(1) :13 -16.
[8] Kimura M,Furukawa M,Izawa E.Report on DEL P1988cruises in the Okinawa Trough;Part 7,Geologic investiga-tions of the central rift in the m iddle to southern OkinawaTrough[J] .Bulletin of the Earthquake Research Institute,U-niversity of Tokyo,1991,66:179-2 0 9.
[9] 业治铮 ,张明书 .Preliminary study on the late Pleistocene andHolocene sediment samples from the Okinawa Trough[J] .海洋地质与第四纪地质 ,1983 ,3 (2 ) :1-2 6.
[10 ] Nagumo S,Kinoshita H,Kasahara J,et al.Report on DEL P1984cruises in the Middle Okinawa Trough Part :Seismicstructural studies[J] .Bulletin of the Earthquake Research In-stitute,University of Tokyo,1986,61:167-2 0 2 .
[11] Yoshii T.U pper mantle structure beneath the North Pacificand the marginal seas[J] .J.Phys.Earth,1973 ,2 1:3 13 -3 2 8.
[12 ] Kaneko Y,Honkura Y.Electrical conductivity structure be-neath the Okinawa Trough and the Ogasawara Arc[J] .Re-portof H rdrographic Res.,1987,2 2 :13 5 -14 3 .
[13 ] Hino R.Crustal structure below the sea-floor around theJapan islands[J] .Journal of Geography,1991,10 0 (4) :5 83 -5 95 .
[14 ] 翟世奎 ,干晓群 .Study on the basalt samples from the hy-drothermal field of the Okinawa Trough[J] .海洋与湖沼学报 ,1995 ,2 6(2 ) :115 -12 3 .
[15 ] Honm a H,Kusakabe M,Kagami H,et al.Major and trace ele-m ent chemistry and D/H,1 8O/1 6 O,87Sr/86 Sr and1 4 3Nd/1 4 4 Ndratios of rocks from spreading center of the OkinawaTrough,a marginal back-arc basin[J] .Geochem.J.,1991,2 5 :12 1-13 6.
[16] Sengor A M C,Burke K.Relative timing of rifting and volcan-ism on Earth and its tectonic implications[J] .Geophys.Res.L ett.,1978,5 :419-4 2
[2 ] Letouzey J,Kimura M.The Okinawa Trough:genesis of aback-arc basin developing along a continental margin[J] .Tectonophysics,1986,12 5 :2 0 9-2 3 0 .
[3 ] Hirata N,Kinoshita H,Katao H,et al.Report on DEL P 1988cruises in the Okinawa Trough part3 :Crustal structure of thesouthern Okinawa Trough[J] .Bulletin of the Earthquake Re-search Institute,University of Tokyo,1991,66:3 7-70 .
[4] 李乃胜 .冲绳海槽海底热流研究 [J] .海洋学报 ,1992 ,14 (4) :87-93 .
[5 ] Kinoshita M,Yamano M,Kasumi Y,et al.Report on DELP1988cruises in the Okinawa Trough part 8:Heat flow m ea-surem ents[J] .Bulletin of the Earthquake Research Institute,University of Tokyo,1991,66:2 11-2 2 8.
[6] Yamano M,Uyeda S,Foucher J P,Sibuet J C.Heat flowanomaly in the middle Okinawa Trough [J] .Tectonophysics,1989,15 9:3 0 7-3 18.
[7] Sato T,Koresawa S,Shioyu Y,Kusano F ,Uechi S,NagaokaO,Kasahara J.Microseismicity of back-arc rifting in the mid-dle Okinawa Trough[J] .Geophs.Res.L etts.,1994,2 1(1) :13 -16.
[8] Kimura M,Furukawa M,Izawa E.Report on DEL P1988cruises in the Okinawa Trough;Part 7,Geologic investiga-tions of the central rift in the m iddle to southern OkinawaTrough[J] .Bulletin of the Earthquake Research Institute,U-niversity of Tokyo,1991,66:179-2 0 9.
[9] 业治铮 ,张明书 .Preliminary study on the late Pleistocene andHolocene sediment samples from the Okinawa Trough[J] .海洋地质与第四纪地质 ,1983 ,3 (2 ) :1-2 6.
[10 ] Nagumo S,Kinoshita H,Kasahara J,et al.Report on DEL P1984cruises in the Middle Okinawa Trough Part :Seismicstructural studies[J] .Bulletin of the Earthquake Research In-stitute,University of Tokyo,1986,61:167-2 0 2 .
[11] Yoshii T.U pper mantle structure beneath the North Pacificand the marginal seas[J] .J.Phys.Earth,1973 ,2 1:3 13 -3 2 8.
[12 ] Kaneko Y,Honkura Y.Electrical conductivity structure be-neath the Okinawa Trough and the Ogasawara Arc[J] .Re-portof H rdrographic Res.,1987,2 2 :13 5 -14 3 .
[13 ] Hino R.Crustal structure below the sea-floor around theJapan islands[J] .Journal of Geography,1991,10 0 (4) :5 83 -5 95 .
[14 ] 翟世奎 ,干晓群 .Study on the basalt samples from the hy-drothermal field of the Okinawa Trough[J] .海洋与湖沼学报 ,1995 ,2 6(2 ) :115 -12 3 .
[15 ] Honm a H,Kusakabe M,Kagami H,et al.Major and trace ele-m ent chemistry and D/H,1 8O/1 6 O,87Sr/86 Sr and1 4 3Nd/1 4 4 Ndratios of rocks from spreading center of the OkinawaTrough,a marginal back-arc basin[J] .Geochem.J.,1991,2 5 :12 1-13 6.
[16] Sengor A M C,Burke K.Relative timing of rifting and volcan-ism on Earth and its tectonic implications[J] .Geophys.Res.L ett.,1978,5 :419-4 2
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