冲绳海槽中段地球物理场及对其新生洋壳的认识  

PRELIMINARY STUDY ON GEOPHYSICAL FIELD AND THE NEW CRUST IN THE MIDDLE OF THE OKINAWA TROUGH

作　　者：梁瑞才[1] 王述功[1] 吴金龙[1] 

机构地区：[1]国家海洋局第一海洋研究所,青岛266061

出　　处：《海洋地质与第四纪地质》2001年第1期57-64,共8页Marine Geology & Quaternary Geology

摘　　要：通过对冲绳海槽中段的磁场进行分析 ,在海槽轴部追踪到了线性磁条带异常。另外 ,在扩张轴附近也拖到了新鲜拉斑玄武岩。重力自由空气异常值较低 ,据信这是由于深部地幔大幅上升所致。地震剖面及磁力资料显示在海槽轴部有强磁性浅层侵入体及海底山 ,这些侵入体很可能来自于深部地幔。高温地幔物质上涌在海槽轴部形成高热流、强磁异常、多火山以及热液活动。上述现象说明冲绳海槽中段张裂轴部大陆岩石圈已经破裂 。By analyzing the magnetic data from the middle Okinawa Trough,we identified the linear magnetic anomalies at the spreading center of the trough,whose spreading age was 0～2 43 MaBP. The fresh tholeiites have been collected near the spreading center,with the newest dating of 0 3 MaBP. Gravity free air anomalies are lower,the crust thickness in the middle of the Trough is gravitationally calculated to be about 20 km,and it is the result that the deep mantle has been uplifted.Single channel seismic reflection profiles and the magnetic data show that there are some shallw intrusions and bottom mountains,and we realize that the young basic intrusions were from deep mantle.The uplifting of the high temperature mantle materials formed high heat flow,strong magnetic anomalies,strong volcanism and hot brine activities.All above suggest that the continental lithosphere has been broken at the axial part of the middle Okinawa Trough,and the new oceanic crust may have been formed at the central spreading center.

关 键 词：磁条带异常 扩张轴 岩石圈 岩浆活动 冲绳海槽 地球物理场 磁性侵入体 

分 类 号：P736.15[天文地球—海洋地质] P738[天文地球—海洋科学]