Zhu Weiling, Ji Yingfeng, Liu Lijun, Qu Rui, Zhu Ye, Xie Chaodi, Ding Lin
State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
iScience. 2023 Jul 11;26(8):107288. doi: 10.1016/j.isci.2023.107288. eCollection 2023 Aug 18.
Previous subduction thermal models are inconsistent with the values of forearc heat flow (50-140 mW/m) and global P‒T conditions of exhumed rocks, both suggesting a shallow environment 200-300°C warmer than model predictions. Here, we revaluate these problems in Kuril-Kamchatka using 3D thermomechanical modeling that satisfies the observed subduction history and slab geometry, while our refined 3D slab thermal state is warmer than that predicted by previous 2D models and better matches observational constraints. We show that warmer slabs create hierarchical slab dehydration fronts at various forearc depths, causing fast and slow subduction earthquakes. We conclude that fast-to-slow subduction earthquakes all play a key role in balancing plate coupling energy release on megathrusts trenchward of high P-T volcanism.
以往的俯冲热模型与弧前热流值（50-140毫瓦/平方米）以及折返岩石的全球P-T条件不一致，这两者都表明存在一个比模型预测温度高200-300°C的浅部环境。在此，我们利用满足观测到的俯冲历史和板块几何形状的三维热机械模型，重新评估了千岛-堪察加地区的这些问题，而我们改进后的三维板块热状态比先前二维模型预测的更温暖，并且能更好地匹配观测约束。我们表明，更温暖的板块在不同的弧前深度产生分层的板块脱水前沿，引发快速和慢速俯冲地震。我们得出结论，快速到慢速俯冲地震在平衡高P-T火山作用向海沟一侧的巨型逆冲断层上的板块耦合能量释放方面都起着关键作用。
