The thermal structure of subduction zones predicted by plate cooling models with variable thermal properties
The thermal structure of subduction zones predicted by plate cooling models with variable thermal properties
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具有可变热特性的板冷却模型预测俯冲带的热结构
DOI：
10.1093/gji/ggac008
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发表时间：
2022
影响因子：
2.8
通讯作者：
Morishige M
中科院分区：
文献类型：
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作者：
安井悠介，松井宏樹;木村友亮;坂田雅文;佐々木重雄;勝俣麻，夏目宏一，永江峰幸，丹羽健，木村友亮，坂田雅文，佐々木重雄;Morishige M
以前的模拟研究调查了实验限制的热特性（即导热率、比热和热膨胀系数）对俯冲带热结构的影响。然而，这些研究没有仔细考虑俯冲前假设的板片热结构是否与地球物理观测相一致。本研究调查的热性能的影响，日本东北部的东北俯冲带的热结构，通过使用板的温度在沟槽板冷却模型确定。三种类型的热性能进行了测试：恒定的，温度依赖和温度和岩性依赖型。对于每种情况，板冷却模型的参数推断的基础上观察到的表面热流和海底深度使用贝叶斯定理。结果发现，预测的温度和相边界的位置在板，这可能是与中深地震，是相似的三种情况。这表明，在东北俯冲带，恒定的热特性可以用于模拟研究与板块脱水有关的现象。大洋板块和板块中等温线的深度不确定性随温度增加而增加，600和1200 °C等温线的深度不确定性分别约为±10和±20 km。当考虑这种不确定性时，蛇纹岩出边界的位置与双地震带的下平面的位置相匹配，这表明脱水可能在触发中深度地震活动中起重要作用。然而，很大的不确定性使得很难详细讨论板内地震的起源，岩石圈-软流圈边界，以及板片的温度下边界。
Previous modelling studies have investigated the effects of experimentally constrained thermal properties (i.e. thermal conductivity, specific heat and the thermal expansion coefficient) on the thermal structure of subduction zones. However, these studies have not carefully considered whether the assumed thermal structure of the slab before subduction is consistent with geophysical observations. This study investigates the effects of thermal properties on the thermal structure of the Tohoku subduction zone, northeast Japan, by using the slab temperature at the trench determined from plate cooling models. Three types of thermal properties were tested: constant, temperature-dependent and temperature- and lithology-dependent types. For each case, the parameters for the plate cooling models were inferred based on the observed surface heat flow and seafloor depth using Bayes’ theorem. It was found that the predicted temperature and location of phase boundaries in the slab, which are possibly related to intermediate-depth earthquakes, are similar for the three cases. This suggests that, in the Tohoku subduction zone, constant thermal properties can be used in modelling to examine phenomena related to slab dehydration. The depth uncertainties for isotherms in the oceanic plate and slab increase with temperature, and are about ±10 and ±20 km for the 600 and 1200 °C isotherms, respectively. When this uncertainty is considered, the location of the serpentinite-out boundary matches that of the lower plane of double seismic zone, suggesting that dehydration may be important in triggering intermediate-depth seismicity. However, the large uncertainty makes it difficult to discuss in detail the origins of intraplate earthquakes, the lithosphere–asthenosphere boundary, and the lower boundary of the slab in terms of temperature.