The southern Chile subduction zone is a complex tectonic environment, where the Chile Ridge, the Nazca (NZ) and Antarctic (AN) plates subduct underneath the South American (SA) plate. The intersection between the NZ, AN and SA plates is referred to as the Chile Triple Junction (CTJ). In this region, a gap, often referred to as a slab window, has been formed between the NZ and AN slabs due to the divergence in their plate motion velocities, with volcanoes existing mainly above the subducted NZ and AN plates. In this study, we constructed a three-dimensional thermomechanical model associated with simultaneous subduction of the NZ and AN plates near the CTJ. The results show that the current temperature distributions on the upper surface of the slabs are higher closer to the Chile Ridge, and the AN plate has a distribution of elevated temperatures relative to the NZ plate at the same depth due to the northward migration of the CTJ and the slower convergence rate of the AN plate. Moreover, we calculated the water content and dehydration gradient from the temperature distribution near the upper surface of the slab and discussed their relationship to the distribution of volcanoes. In the northern part of the model domain, high dehydration gradients were obtained below the volcanic chain. Therefore, we suggest that the water released from the slab and the mantle wedge decreased the melting point of the mantle wedge just above the slab and produced melts, which may have contributed to form the overlying volcanoes.

中文翻译：

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智利三重交界处附近的三维热结构和脱水及其与板窗、构造震动和火山的关系

智利南部俯冲带是一个复杂的构造环境，智利海岭、纳斯卡（NZ）和南极（AN）板块俯冲到南美（SA）板块下方。NZ、AN 和 SA 板块之间的交叉点称为智利三重交汇处 (CTJ)。在该区域，由于新西兰板块和AN板块运动速度的差异，在NZ板块和AN板块之间形成了一个间隙，通常被称为板片窗口，火山主要存在于俯冲的NZ和AN板块上方。在这项研究中，我们构建了一个与 CTJ 附近 NZ 和 AN 板块同时俯冲相关的三维热机械模型。结果表明，靠近智利海脊的板块上表面当前温度分布较高，由于CTJ向北迁移和AN板块收敛速度较慢，AN板块在同一深度处相对于NZ板块呈现升高的分布。此外，我们还根据板片上表面附近的温度分布计算了含水量和脱水梯度，并讨论了它们与火山分布的关系。在模型域的北部，火山链下方获得了高脱水梯度。因此，我们认为板片和地幔楔释放的水降低了板片上方地幔楔的熔点并产生熔体，这可能有助于形成上覆火山。