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冲绳海槽位于西太平洋活动大陆边缘,是一个目前正处于弧后扩张作用早期的、年轻的弧后盆地,张性断裂发育,火山活动强烈.岩石类型分布和岩石地球化学特征表明冲绳海槽中部和南部的岩浆作用存在明显差异,但迄今为止人们对于导致该差异的原因尚不清楚.对已有的冲绳海槽玄武岩的资料进行了综合对比分析,并依据冲绳海槽岩浆岩的Pb同位素组成特征,指出冲绳海槽及其所在的沟弧盆体系之下的地幔属于印度洋型地幔,相对于海槽中部的玄武岩岩浆,海槽南部的玄武岩岩浆来自地幔更高程度的熔融;冲绳海槽玄武岩岩浆受到了俯冲板块物质加入的影响,且南部玄武岩岩浆受影响的程度要高于中部,这可能受控于俯冲板块的深度(南部:100~150km;中部:约200km);冲绳海槽玄武岩部分属于MORB型,这应是冲绳海槽早期扩张的重要特征和证据之一.在上述分析工作的基础上,提出了今后对冲绳海槽岩浆作用的研究应主要集中在以下几个方面:冲绳海槽基底岩石类型的甄别与分布;岩浆源区地幔的类型及特征;板块俯冲对冲绳海槽岩浆作用的贡献及制约机制;冲绳海槽岩浆作用与海底热液活动的内在联系等.
The Okinawa Trough is located on the margin of the western Pacific margin and is a young back-arc basin that is currently in the wake of post-arc dilation. The Zhangjiakou fault developed with strong volcanic activity. The distribution of rock types and geochemical characteristics of the rocks show that the central part of the Okinawa Trough And the magma in the south have obvious differences, but the reason why the difference is so far unknown is clear.On the basis of a comprehensive comparative analysis of the existing data of the basalt in the Okinawa Trough, and based on the Pb isotope composition of the magmatic rocks in the Okinawa Trough It is pointed out that the mantle under the Okinawa Trough and the arc-arc basin system in which the Okinawa Trough is located belongs to the Indian Ocean mantle. Basalt magma in the southern part of the trough comes from a higher degree of melting of the mantle relative to basaltic magma in the central trough. Influenced by the addition of subducted slab mass and the southern basalt magma affected more than the middle part, which may be controlled by the depth of the subducted slab (southern part: 100-150 km; middle part: about 200 km); part of the Okinawa Trough basalts belongs to MORB type, which should be one of the important features and evidence of the early expansion of the Okinawa Trough.Based on the above analysis, The future research on the magmatism of the Okinawa Trough should mainly focus on the following aspects: the screening and distribution of basement rock types in the Okinawa Trough; the types and characteristics of mantle in the magma source area; the contribution of plate subduction to the magmatism in the Okinawa Trough And constraints; the intrinsic relationship between the Okinawa Trough magmatism and seafloor hydrothermal activity.