Probing the Chilean subduction zone at mantle depths:Insights from Patagonian High-Pressure rocks

尽管过去30年来的许多地球物理研究记录了智利俯冲带的结构和动力学，但深度超过40公里的构造和动力学仍然没有得到很好的解决。本文建议对智利巴塔哥尼亚迭戈德阿尔马格罗岛(Diego de Almagro Island，巴塔哥尼亚)蓝片岩-榴辉岩相(40-50公里)中唯一的高压变质地体进行研究，以突出智利深部(40-50公里)俯冲带中的增积作用和流体-岩石相互作用过程。该岛的内部结构显然是由来自不同来源的物质和变质历史构成的，需要进一步描述其地质史。实地活动将使：(1)在全岛实现广泛的取样和结构测量；(2)实现全岛的第一个地质横截面；(3)为建造该岛的各个子单位提供详细的压力-温度-时间-变形路径。我们的方法的优点是将现代温压测量工具与原位Ar-Ar年代学约束和Rb-Sr形变年龄相结合。这些结果将对改善我们对智利俯冲通道的岩性组成和结构以及植根于孕震带底部的变形过程的看法具有重要意义。这一结果也将有助于揭示莫霍面深度的俯冲界面动力学，因此对地球物理学家群体具有重要意义。

Even though documented by numerous geophysical studies over the last 30 years, the Chilean subduction zone structure and dynamics at depths greater than 40 km remains poorly resolved. We herein propose to study the only high-pressure metamorphic terrane from the Chilean margin exhumed from blueschist-to-eclogite facies (40-50 km depth) on the Diego de Almagro Island (Patagonia, Chile), to highlight accretionary and fluid-rock interaction processes in the deep (40-50 km) Chilean subduction zone. The internal structure of the Island, which is apparently constituted by material from various origins and metamorphic histories, needs further characterization of its geological history. The field campaign will permit (i) to realize a widespread sampling and structural measurements throughout the Island (ii) to realize the first geological cross-section across the island and (iii) to perform detailed pressure-temperature-time-deformation paths for the various sub-units building up the island. The strength of our approach is to combine modern thermobarometric tools with in situ Ar-Ar geochronological constrains and Rb-Sr deformation ages. These results will be of importance to improve our vision of the lithological composition and structure of the Chilean subduction channel as well as of deformation processes rooted at the base of the seismogenic zone. The results will also shed light on subduction interface dynamics at Moho depths and will therefore be of importance of the geophysicists community.