Tectonophysical Features of the Hydrothermal Fields in the Middle Okinawa Trough
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摘要: 对冲绳海槽中部南奄西、伊平屋、伊士名三个现代海底热液活动区的地形、热流分布、地震、地磁场特征进行了初步研究。结果表明,海槽中部的热液活动区都集中于海槽的中央地堑中,或位于火山口的侧坡上,或位于地堑中山脊的侧坡上,热流值高而变化大,地震事件十分上频繁,地磁场曲线变化较大。这一系列特征说明现代海底热液活动区和目前的构造活动带吻合,热液活动和岩浆作用或浅成岩浆房密切相关。板块俯冲在海槽下诱生地幔物质上涌,上涌的地幔物质所携带的热量为热液活动提供了动力源,在海槽拉张过程中形成的断裂为热液流体提供了运移通道.Abstract: Hvdrothermal activity is widely occurring along the active plate boundaries and intraplate volcanic centers which is exchanging heat and material between the lithosphere and the oceans.Okinawa Trough is an important part of Rvukv T-A-ha system汕ich is in the collision and suhduction zone between a oceanic block and continental block and is reported to he in the early stage of back-arc spreading with a rift structure and an embryonic marginal hasin} its origin and evolution may he one of the most interseting problems in geophysics and geology today.Hvdrothermal activity as a window and clue of studying the origin and evolution of Okinawa Trough has been explored through out the Trough by scientists all over the worlds.Sever- al hvdrothermal fields have been found in the middle part of Okinawa Trough.Tectonophysical features of topography heatflow distrihution, seismicitv and magnetic anomaly of three hvdrothermal fields including southwest Amami hvdrothermal field.Iheva deep hydrothermal field and Izena caldron hvdrothermal field in the middle Okinawa Trough were studied. The results show that all the hvdrothermal fields distribute in the central grahen and locate at the slope of caldera or of central ridge with high and vary heatflow distrihution, active seismic activities and fluctuating magnetic anomaly.It is found that the hvdrothermal fields have close relationship with tectonic zoon.In the area of Rvukvu T-A-Ba svstem, the upwelling of mantal materials beneath the trough due to the suhduction of Pacific Plate provides heat energy for the hvdrothermal activity.The faults formation in the process of trough expending provides space for the hydrothermal activity.
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Key words:
- Okinawa Trough /
- hydrothermal fields /
- tectonophysical features
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