Collaborative Research: Lithospheric Dynamics in the Southernmost Andean Plateau

本文将通过在安第斯高原中部普纳南部进行的国际被动震源合作地震实验，探讨沿安第斯型大陆边缘形成、改变和破坏大陆岩石圈的过程以及控制岩石圈动力学的基本问题。南普纳（南纬25度~南纬28度）不仅是了解安第斯山脉演化的关键，也是检验加厚的榴辉岩大陆地壳与大陆地幔岩石圈剥离假说的类型场所。这种地壳的移除解释了为什么在许多造山区（包括北部的安第斯高原中部）几乎没有致密的基性根，以及同样（如果不是更重要的话）大陆地壳的大块安山岩成分。在此，我们建议获取所需的详细地球物理数据，以测试当前岩石圈结构是否与这一过程相容，并填补安第斯高原中部独特地区沿走向的现代地球物理覆盖的关键空白。该项目将部署共25个宽带和45个中期三成分地震台站，并采用一些新的和成熟的技术来成像岩石圈地震速度结构和当地地震活动模式的细节。这是一个真正的国际项目，因为它将受益于来自美国、德国和南美的科学家的参与。这些图像将与区域地质和相关火山活动的地球化学特征相结合，形成一个强大的安第斯山脉中部带演化的地球动力学模型。我们打算结合地震层析成像方法（面波、体波和衰减）以及该地区大量的先前地质研究来研究与板块岩石圈相关的地幔动力学和地幔流动，以帮助限制南普纳高原岩石圈移动的范围、时间和数量。这项工作将培养一批美国、德国和阿根廷的现代地震数据采集和处理学生。这项研究将有助于更好地了解安第斯山脉地震和火山灾害的更广泛方面，这些灾害具有毁灭性的潜力，以及这一经典矿物地体中自然资源的来源。最后，这项研究为计划中的EARTHSCOPE对美国西部更古老的、可比较的造山带系统进行调查提供了一个先行者和地球动力学参考

0538245SandvolCollaborative Research: Lithospheric Dynamics in the Southernmost Andean Plateau We will address the fundamental questions on the processes that form, modify and destroy continental lithosphere and control lithospheric dynamics along Andean-type continental margins through a collaborative international passive-source seismic experiment in the southern Puna of the central Andean plateau. The southern Puna (25 degrees S to 28 degrees S) is not only key to understanding Andean evolution, it is also the type locale for testing the delamination hypothesis for removal of thickened eclogitic continental crust along with continental mantle lithosphere. Such crustal removal provides an explanation for the near absence of a dense mafic root in many orogenic regions (including the central Andean plateau to the north) as well as the equally, if not more important, bulk andesitic composition of the continental crust. We here propose to acquire the detailed geophysical data needed to test whether current lithospheric structure is compatible with this process, as well as to fill in a critical gap in modern geophysical coverage along strike in a distinctive part of the central Andean plateau.This project will involve deploying a total of 25 broadband and 45 intermediate-period three component seismic stations and employing a number of new and well-established techniques to image the details of the lithospheric seismic velocity structure and local seismicity patterns. This is a truly international project in that it will benefit from the participation of scientists from the U.S., Germany, and South America. The images will be integrated with the regional geology and the geochemical signature of relevant volcanism to form a robust geodynamic model for the evolution of the central Andean mountain belt. We intend to study mantle dynamics and mantle flow associated with slab lithosphere using a combination of seismic tomographic methods (surface wave, body wave, and attenuation) as well as the large volume of prior geologic studies in this region to help constrain the extent, timing and amount of lithospheric removal within the southern Puna plateau. This work will train a number of American, German, and Argentine students in modern seismological data acquisition and processing. The study will contribute to improved understanding of the broader aspects of the earthquake and volcanic hazards in the Andes which have devastating potential, as well as the origin of natural resources in this classic mineral terrane. Lastly, this study serves as a forerunner and geodynamic reference for planned EARTHSCOPE investigations of older, comparable orogenic systems in the western U.S.