Collaborative Research: Characterizing and Modeling Crustal Recycling

地壳向下循环到地球深处的过程被用来解释各种各样的地球过程，包括移动构造板块的力量的变化，以及地壳的厚度和组成是如何演变的。所有这些过程都发生在人类无法到达的深处。塔吉克斯坦帕米尔山脉的一次火山爆发使地球深处90公里处的岩石碎片浮出水面，这些岩石碎片可用于测试与回收有关的假设。该项目将为研究生Madeline Shaffer和几名本科生提供培训和研究机会。对当地小学的访问将使潜在的未来科学家接触地球科学。激光烧蚀分流技术的持续发展将使他们实验室的广大参观者受益。这个美国-塔吉克斯坦-罗马尼亚合作项目有两个方面的方法：1）实验室地质年代学和岩石学，这将限制回收的时间尺度，以及回收材料的成分，密度和波速。通过对原岩成分的一些假设，可以计算出这些物理性质的演化。2)不同热梯度下不同成分和层次的地壳剖面再循环的地球动力学模拟。这些模型将计算出再循环地壳物理性质的演变，并确定可能再循环的地壳剖面类型。由于帕米尔-青藏高原是典型的大陆-大陆碰撞，在那里发展的思想可以在全球应用。

Recycling of Earth's crust back down into the deep Earth has been invoked to explain a wide variety of Earth processes, including changes in the forces that move tectonic plates, and how the thickness and composition of Earth's crust evolved. All of these processes take place at depths inaccessible to humans. A volcanic eruption in the Pamir Mountains of Tajikistan has brought to light pieces of rock from 90 km deep in Earth that can be used to test recycling-related hypotheses. This project will provide training and research opportunities for graduate student Madeline Shaffer and several undergraduate students. Visits to local elementary schools will expose potential future scientists to Earth science. Continued development of the laser-ablation split-stream technique will benefit the broad range of visitors to their laboratory.This collaborative US-Tajik-Romanian project has a two-pronged approach: 1) Laboratory geochronology and petrology that will constrain the timescale of recycling, and the compositions, densities and wavespeeds of the recycling materials. With some assumptions about protolith composition, the evolution in these physical properties can be calculated. 2) Geodynamic modeling of recycling crustal sections with different compositions and layers in different thermal gradients. The models will yield the calculated evolution of the physical properties of recycling crust and determine the types of crustal sections that may recycle. Because the Pamir-Tibetan Plateau is an archetypal continent-continent collision, ideas developed there can be applied globally.