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日本俯冲带与IBM俯冲带位于太平洋板块、菲律宾海板块和欧亚板块三者的交汇地带,是典型的“俯冲工厂”地区,具有重要的研究意义.本文利用震源分布资料与卫星重力数据对日本俯冲带与IBM俯冲带进行了研究.通过空间重力异常反映了俯冲带地区的区域构造形态,在此基础上基于艾利模式计算了均衡异常以反映地壳均衡特征.利用震源分布资料,分别从垂直俯冲带走向与沿俯冲带走向划定了横截剖面(cross-sections)进行了地震提取,讨论了俯冲带地区的Wadati-Benioff带形态特征,并借助于俯冲带地震等深线图直观描述了俯冲带的俯冲形态.在日本俯冲带与伊豆—小笠原俯冲带各选取了一条典型剖面进行了重力2.5D反演,研究了俯冲带地区的壳幔结构特征.研究结果表明,九州—帕劳海脊与IBM岛弧在均衡异常上存在差异,前者已逐渐趋向于地壳均衡.IBM的Wadati-Benioff带存在明显的南北差异,反映出伊豆—小笠原俯冲板片停留在了660km转换带中,而马里亚纳俯冲板片很可能垂直穿过了这一转换带,造成这种南北差异的原因与板块相对运动、岩石圈黏性和年龄差异以及俯冲板片的重力效应等因素有关.在IBM的中部和南部存在板片撕裂现象.日本俯冲带的俯冲洋壳密度随俯冲深度变化较小,洋幔存在一定程度的蛇纹岩化,地幔楔蛇纹岩化作用不典型,海沟处有一范围较小的含水畸变带;伊豆—小笠原俯冲带俯冲洋壳密度随深度增大而明显增大,洋幔蛇纹岩化程度较日本俯冲带低,地幔楔蛇纹岩化作用强烈,板块交汇处存在明显的蛇纹岩底辟.日本俯冲带与IBM俯冲带一线自北向南板片俯冲变陡,两侧板块耦合度降低,与俯冲带两侧的板块运动速率差异有关.
The subduction zone of Japan and the IBM subduction zone are located in the intersection of the Pacific plate, the Philippine sea plate and the Eurasian plate, which is a typical “subduction factory” region, which is of great research significance.This paper uses the source distribution data and satellite gravity data The subduction zones of Japan and IBM are studied, and the regional structural patterns of the subduction zone are reflected by the spatial gravity anomalies, on the basis of which, the equilibrium anomalies are calculated to reflect the crustal equilibrium characteristics.According to the source distribution data, The seismic extraction was carried out from the vertical subduction zone and the cross-sections along the trend of the subduction zone. The Wadati-Benioff zone morphological characteristics of the subduction zone were discussed. With the aid of the contour map of the subduction zone, Describes the subduction state of the subduction zone.A typical section is selected for a typical section in Japan subduction zone and Izu-Ogasawara subduction zone to conduct gravity 2.5D inversion to study the structural features of the crust and mantle in the subduction zone.The results show that Kyushu-Pa There are differences in the anomalous anomalies between the Loess ridge and the IBM island arc, and the former tends to crustal equilibrium. The Wadati-Benioff belt of IBM has obvious The difference between North and South reflects that the Izu-Ogasawara subduction plate stays in the 660km transition zone, and the Mariana dive plate is likely to cross this transition zone perpendicularly, causing this difference between north and south to move relative to the plate, Lithospheric viscosity and age differences, as well as the gravity effect of subducting slab and other factors.The plate tearing exists in the central and southern part of IBM.The subductional oceanic shell densities in Japan subduction zone vary little with the subduction depth, and the mantle has a certain The degree of serpentinization, the mantle wedge serpentinization is not typical, the trench has a smaller range of water-bearing distortion zone; Izu - Ogasawara subduction zone of the subducting oceanic shell density increases with depth, the mantle serpentine The degree of lithification is lower than that of Japanese subduction zone, and the mantle wedge serpentinization is strong with obvious serpentin diapir. At the intersection of Japan subduction zone and IBM subduction zone, the subduction from north to south plate becomes steep, both sides plate Coupling degree decreases, which is related to the difference of plate moving velocity on both sides of subduction zone.