Mantle Wedge Flow Pattern and Thermal Structure in Northeast Japan: Effects of Oblique Subduction and 3-D Slab Geometry
Mantle Wedge Flow Pattern and Thermal Structure in Northeast Japan: Effects of Oblique Subduction and 3-D Slab Geometry
复制标题
日本东北部的地幔楔流动模式和热结构：倾斜俯冲和 3-D 板片几何形状的影响
DOI：
10.1016/j.epsl.2015.06.021
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发表时间：
2015
影响因子：
5.3
通讯作者：
and Junichi Nakajima
中科院分区：
文献类型：
--
作者：
Ikuko Wada; Jiangheng He;Akira Hasegawa;and Junichi Nakajima
我们开发了一个3-D的日本东北俯冲边缘的热模型，使用一个现实的板块俯冲太平洋板块的几何形状，并调查斜俯冲和3-D板几何形状的地幔楔流模式和热结构的影响。在东北地区，地幔楔流模式几乎是二维的热结构类似于通过2-D模型获得的，由于简单的板状几何形状和俯冲几乎垂直于边缘。然而，在北海道，斜向俯冲导致三维地幔楔流与北流入和西北西流出，也导致在较低的温度在地幔楔的浅部比东北地区由于较低的下沉速率板。在北海道和东北之间，由于倾向方向的相对急剧变化，板片具有铰链状形状。在这个枢纽带，来自北海道的偏北地幔流入和来自东北的偏西地幔流入汇合，阻碍了来自西北的地幔流入，导致了较冷的地幔楔。模型预测的地幔楔流模式与观测到的地震各向异性是一致的，可以解释火山交叉链的方向。预测的3-D热结构相关性以及沿弧变化的位置的前弧火山，并有助于提供新的见解的表面热流模式和下倾程度的板间地震。
We develop a 3-D thermal model for the Northeast Japan subduction margin, using a realistic slab geometry for the subducting Pacific plate, and investigate the effects of oblique subduction and 3-D slab geometry on the mantle wedge flow pattern and the thermal structure. In the Tohoku region, the mantle wedge flow pattern is nearly two-dimensional resulting in a thermal structure similar to those obtained by a 2-D model, owing to the simple slab geometry and subduction nearly perpendicular to the margin. However, in Hokkaido, oblique subduction leads to 3-D mantle wedge flow with northerly inflow and west–northwestward outflow and also results in lower temperatures in the shallow part of the mantle wedge than in Tohoku due to lower sinking rate of the slab. Between Hokkaido and Tohoku, the slab has a hinge-like shape due to a relatively sharp change in the dip direction. In this hinge zone, northerly mantle inflow from Hokkaido and westerly mantle inflow from Tohoku converge, discouraging inflow from northwest and resulting in a cooler mantle wedge. The model-predicted mantle wedge flow patterns are consistent with observed seismic anisotropy and may explain the orientations of volcanic cross-chains. The predicted 3-D thermal structure correlates well with the along-arc variations in the location of the frontal arc volcanoes and help to provide new insights into the surface heat flow pattern and the down-dip extent of interplate earthquakes.