千岛-勘察加俯冲带俯冲特征的空间差异性及成因的初步探讨

Spatial difference and its impact on the subduction characteristics of the Kuril–Kamchatka subduction zone

基于地震震中分布、地震层析成像方法,系统阐述了俯冲带从南到北俯冲角度、俯冲深度、形态以及板上地幔楔熔融程度等方面的空间差异特征,同时结合岛弧火山岩中的Sr、Nd、Pb同位素信息进一步探讨了该区域岩浆作用的空间差异性,最终将千岛-勘察加俯冲带分为6段。综合以往研究可知,俯冲带分段性的成因比较复杂,与岩浆源区地幔中流体成分和含量、板片与海沟的汇聚速率、沿贝尼奥夫带的应力状态等皆有着密切的联系,而基于板块运动模型,板片的汇聚速率与俯冲结构的空间差异性有着较好的对应关系,因此本研究认为板片的汇聚速率是影响该地区空间差异性的重要因素,而更系统的成因有待进一步研究。综合分析千岛-勘察加俯冲带的俯冲特征对于丰富研究区板块构造理论,深入理解俯冲带动力学过程具有重要意义。

Based on the earthquake distribution and seismic tomography method,this paper describes the systematic spatial differences in the angle,depth,and shape of the subducted slab and the degree of melting of the mantle wedge on the subduction zone,from south to north,of the Kuril Kamchatka subduction zone.Sr,Nd,and Pb were also used to further explore the spatial difference in the zone's magmatism.We propose that the Kuril Kamchatka subduction zone can be divided into six segments.Although previous studies have shown that the causes of these spatial differences can be complicated,we found that it may be closely related to the composition and content of the fluid in the mantle,the convergence rate between subducted slab and trench,and the stress along the Wadati-Benioff zone.Among these possible causes,we suggest that the convergence plays an important role in the segmentation since,based on the plate motion model,there is a good correspondence between the convergence rate of the plates and the spatial differences in the subduction structure.Analyzing the subducting characteristics of the Kuril Kamchatka subduction zone is of great significance in enriching the theory of plate tectonics and improving our under- standing of the dynamics of subduction zones.