Collaborative Research: Lithospheric Dynamics in the Southernmost Andean Plateau

合作研究：安第斯高原最南端的岩石圈动力学我们将通过在安第斯高原中部普纳南部开展的国际被动震源地震实验，解决形成、修改和破坏大陆岩石圈的过程的基本问题，并控制安第斯类型大陆边缘的岩石圈动力学。南普纳(S 25度至S 28度)不仅是理解安第斯演化的关键，也是检验加厚榴辉岩陆壳与大陆地幔岩石圈拆沉假说的典型场所。这种地壳迁移解释了为什么许多造山带(包括北部的安第斯高原中部)几乎没有致密的镁铁质岩根，以及大陆地壳的大量安山岩成分，如果不是更重要的话。我们建议获取详细的地球物理数据，以测试目前的岩石圈结构是否符合这一过程，并填补安第斯高原中部一个独特部分沿走向的现代地球物理覆盖的关键空白。该项目将涉及部署总共25个宽带和45个中期三分量地震台，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局部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，形成一个强有力的安第斯山脉中部地带演化的地球动力学模型。我们打算利用地震层析成像方法(面波、体波和衰减)以及该地区以往的大量地质研究相结合的方法来研究与板片岩石圈有关的地幔动力学和地幔流动，以帮助限制普纳高原南部岩石圈移动的程度、时间和数量。这项工作将培训一些美国、德国和阿根廷的学生在现代地震数据采集和处理方面。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，这些方面具有毁灭性的潜力，以及这一经典矿物地体的自然资源来源。最后，这项研究为计划中的地球望远镜调查美国西部较老的、可比较的造山系统提供了先导和地球动力学参考。

0538112KayCollaborative 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.