Along-arc variation in the 3-D thermal structure around the junction between the Japan and Kurile arcs
Along-arc variation in the 3-D thermal structure around the junction between the Japan and Kurile arcs
复制标题
日本弧和千岛弧交界处周围 3D 热结构的沿弧变化
DOI：
10.1002/2014gc005394
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
P. E.
中科院分区：
文献类型：
--
作者：
Morishige;M. and van Keken;P. E.
俯冲带的热结构对地震成因和弧火山活动有很大的影响。传统的2-D模型已被用于提供模型和观测值之间的合理一致性，但在许多情况下，存在明显的3-D效应。北方日本俯冲系统就是这样一个例子。在日本和千岛群岛弧之间的交界处，地表热流和中深层地震活动的发生与东北和北海道地区不同。基于三维有限元方法，我们研究了三维板几何形状和板幔解耦深度的局部加深对该区域热结构的影响。研究发现，这两种效应都使铸坯表面温度沿沿着弧变化，最高可达100°C。在考虑三维平板几何形状的情况下，较暖的区域是通过三维热传导效应产生的，较冷的区域是通过局部缓慢进入的流动产生的。当假设板幔解耦深度局部加深时，会出现三维流动，这会导致更温暖和更寒冷的区域。对地表热流的影响很小。虽然俯冲地壳中的中深度地震活动被认为是由温度相关的相变控制的，但预测的热结构变化不足以导致观察到的地震活动加深。这表明，该俯冲带的热结构可能更强烈地受到上覆地壳和板片随时间变化的变形的影响。
The thermal structure in subduction zones has a strong influence on seismogenesis and arc volcanism. Traditional 2‐D models have been used to provide reasonable agreement between models and observations, but in a number of cases clear 3‐D effects are present. One such case is in the Northern Japan subduction system. At the junction between Japan and Kurile arcs, surface heat flow and the occurrence of intermediate‐depth seismicity are different than in the Tohoku and Hokkaido regions. We investigate the effects of 3‐D slab geometry and a local deepening of slab‐mantle decoupling depth on the thermal structure in this region based on 3‐D finite element approach. We find that both effects produce the along‐arc variation of slab surface temperature, which could reach ∼100°C. The warmer region arises through 3‐D effects of thermal conduction and the colder region arises through localized slow incoming flow in the case where 3‐D slab geometry is taken into account. 3‐D flow arises where a local deepening of slab‐mantle decoupling depth is assumed, which leads to both warmer and colder regions. The effects on surface heat flow are small. While intermediate‐depth seismicity in the subducted crust is suggested to be controlled by temperature‐dependent phase transitions, the predicted changes in thermal structure are not sufficient to cause the observed deepening of seismicity. This suggests that the thermal structure of this subduction zone may be more strongly influenced by time‐dependent deformation of the overriding crust and slab.