The paper focuses on the characteristics of faulting and magmatism of the Okinawa Trough and the relation between them. En-echelon grabens are ranked oblique to the continental shelf edge uplift, and the Longwang upli...The paper focuses on the characteristics of faulting and magmatism of the Okinawa Trough and the relation between them. En-echelon grabens are ranked oblique to the continental shelf edge uplift, and the Longwang uplift, the rifting block ridge in the northern segment and the ＂Mianhua uplift＂ in the southern segment have possibly preserved characteristics of volcanism and magmatism occurring with those rifting phases. The clockwise rotation of the southern Ryukyu Islands, driven by collision between Luzon and Taiwan, has played a key role in the crustal oceanization, enhancing the crustal extension of the southern segment and inducing volcanic magmatism in those grabens, among which the Yaeyama graben is a typical example of the presence of oceanic crust. Faulting and magmatism were mainly migrating towards the island arc asymmetrically. The crustal oceanization of the Okinawa Trough is difficultly interpreted by the linear magnetic anomaly model, which is fit for the symmetric spreading of the mid-oceanic ridges.展开更多
Okinawa Trough is a back-arc, initial marginal sea basin, located behind the Ryukyu Arc-Trench System. The formation and evolution of the Okinawa Trough is intimately related to the subduction process of the Philippin...Okinawa Trough is a back-arc, initial marginal sea basin, located behind the Ryukyu Arc-Trench System. The formation and evolution of the Okinawa Trough is intimately related to the subduction process of the Philippine Sea Plate beneath the Eurasian Plate since the late Miocene. The tectonic evolution of the trough is similar to other active back-arcs, such as the Mariana Trough and southern Lau Basin, all of which are experiencing the initial rifting and subsequent spreading process. This study reviews all petrologic and geochemical data of mafic volcanic lavas from the Okinawa Trough, Ryukyu Arc, and Philippine Sea Plate, combined with geophysical data to indicate the relationship between the subduction sources （input） and arc or back-arc magmas （output） in the Philippine Sea Plate-Ryukyu Arc-Okinawa Trough system （PROS）. The results obtained showed that several components were variably involved in the petrogenesis of the Oki-nawa Trough lavas：sub-continental lithospheric mantle underlying the Eurasian Plate, Indian mid-oceanic ridge basalt （MORB）-type mantle, and Pacific MORB-type mantle. The addition of shallow aqueous fluids and deep hydrous melts from subducted components with the characteristics of Indian MORB-type mantle into the mantle source of lavas variably modifies the primitive mantle wedge beneath the Ryukyu and sub-continental lithospheric mantle （SCLM） beneath the Okinawa Trough. In the northeastern end of the trough and arc, instead of Indian MORB-type mantle, Pacific MORB-type mantle dominates the magma source. Along the strike of the Ryukyu Arc and Okinawa Trough, the systematic variations in trace element ratios and isotopic compositions reflect the first-order effect of variable subduction input on the magma source. In general, petrologic data, combined with geophysical data, imply that the Okinawa Trough is experiencing the＂seafloor spreading＂process in the southwest segment,＂rift propagation＂process in the middle seg-ment, and＂crustal extension＂process in the northeast segment, and a nascent ocean basin occurs in the southwest segment.展开更多
西南极绕极深层水(CircumpolarDeepWater,CDW)是源于南极绕极流的暖水团,也被认为是多特森—盖茨海槽的热源,但对其气候态分布特征了解甚少。本文基于观测分析数据(EN4)、EstimatingtheCirculation&Climate of theOcean(ECCO)和Cope...西南极绕极深层水(CircumpolarDeepWater,CDW)是源于南极绕极流的暖水团,也被认为是多特森—盖茨海槽的热源,但对其气候态分布特征了解甚少。本文基于观测分析数据(EN4)、EstimatingtheCirculation&Climate of theOcean(ECCO)和Copernicus Global (1/12)°Oceanic and Sea Ice(GLORYS12)再分析资料,分析了多特森—盖茨海槽CDW水团夏季(1月)的气候态分布特征。结果表明, CDW上边界深度沿西阿蒙森海海盆纬向断面呈现一定的纬向变化, CDW温度和盐度分别达到1℃和34.7;CDW上边界深度沿多特森—盖茨海槽断面具有一定的变化,相应的CDW温度和盐度分别高于0℃和34.6;对于跨多特森—盖茨海槽断面, CDW温度和盐度存在东西向差异,海槽东侧CDW温度和盐度较高。展开更多
基金The National Major Fundamental Research and Development Project of China under contract Nos G2000046703 and 2007CB411702the Scientific Research Fund of the Second Institute of Oceanography, State Oceanic Administration under contract No.JT0705
文摘The paper focuses on the characteristics of faulting and magmatism of the Okinawa Trough and the relation between them. En-echelon grabens are ranked oblique to the continental shelf edge uplift, and the Longwang uplift, the rifting block ridge in the northern segment and the ＂Mianhua uplift＂ in the southern segment have possibly preserved characteristics of volcanism and magmatism occurring with those rifting phases. The clockwise rotation of the southern Ryukyu Islands, driven by collision between Luzon and Taiwan, has played a key role in the crustal oceanization, enhancing the crustal extension of the southern segment and inducing volcanic magmatism in those grabens, among which the Yaeyama graben is a typical example of the presence of oceanic crust. Faulting and magmatism were mainly migrating towards the island arc asymmetrically. The crustal oceanization of the Okinawa Trough is difficultly interpreted by the linear magnetic anomaly model, which is fit for the symmetric spreading of the mid-oceanic ridges.
基金The National Natural Science Foundation of China under contract Nos 41322036,41230960,40906034,41276003 and 41176058China Ocean Mineral Resources R&D Association(COMRA)under contract No.DY125-12-R-05
文摘Okinawa Trough is a back-arc, initial marginal sea basin, located behind the Ryukyu Arc-Trench System. The formation and evolution of the Okinawa Trough is intimately related to the subduction process of the Philippine Sea Plate beneath the Eurasian Plate since the late Miocene. The tectonic evolution of the trough is similar to other active back-arcs, such as the Mariana Trough and southern Lau Basin, all of which are experiencing the initial rifting and subsequent spreading process. This study reviews all petrologic and geochemical data of mafic volcanic lavas from the Okinawa Trough, Ryukyu Arc, and Philippine Sea Plate, combined with geophysical data to indicate the relationship between the subduction sources （input） and arc or back-arc magmas （output） in the Philippine Sea Plate-Ryukyu Arc-Okinawa Trough system （PROS）. The results obtained showed that several components were variably involved in the petrogenesis of the Oki-nawa Trough lavas：sub-continental lithospheric mantle underlying the Eurasian Plate, Indian mid-oceanic ridge basalt （MORB）-type mantle, and Pacific MORB-type mantle. The addition of shallow aqueous fluids and deep hydrous melts from subducted components with the characteristics of Indian MORB-type mantle into the mantle source of lavas variably modifies the primitive mantle wedge beneath the Ryukyu and sub-continental lithospheric mantle （SCLM） beneath the Okinawa Trough. In the northeastern end of the trough and arc, instead of Indian MORB-type mantle, Pacific MORB-type mantle dominates the magma source. Along the strike of the Ryukyu Arc and Okinawa Trough, the systematic variations in trace element ratios and isotopic compositions reflect the first-order effect of variable subduction input on the magma source. In general, petrologic data, combined with geophysical data, imply that the Okinawa Trough is experiencing the＂seafloor spreading＂process in the southwest segment,＂rift propagation＂process in the middle seg-ment, and＂crustal extension＂process in the northeast segment, and a nascent ocean basin occurs in the southwest segment.
文摘西南极绕极深层水(CircumpolarDeepWater,CDW)是源于南极绕极流的暖水团,也被认为是多特森—盖茨海槽的热源,但对其气候态分布特征了解甚少。本文基于观测分析数据(EN4)、EstimatingtheCirculation&Climate of theOcean(ECCO)和Copernicus Global (1/12)°Oceanic and Sea Ice(GLORYS12)再分析资料,分析了多特森—盖茨海槽CDW水团夏季(1月)的气候态分布特征。结果表明, CDW上边界深度沿西阿蒙森海海盆纬向断面呈现一定的纬向变化, CDW温度和盐度分别达到1℃和34.7;CDW上边界深度沿多特森—盖茨海槽断面具有一定的变化,相应的CDW温度和盐度分别高于0℃和34.6;对于跨多特森—盖茨海槽断面, CDW温度和盐度存在东西向差异,海槽东侧CDW温度和盐度较高。
