CAREER: Developing New Methodologies to Investigate the Thermal, Tectonic, and Climatic History of Continental Settings - An Integrated Educational and Research Project

二十多年来，人们一直认为热和氦在地壳中的输运性质相似，两种示踪剂的输运都处于稳定状态。此外，根据在洋中脊附近观测到的低地幔He/热通量比，提出了地球氦热不平衡的存在。然而，最近的研究表明，这两种示踪剂的驱动输运机制在地壳中岩石渗透率较高的情况下具有根本不同的性质。结果表明，稳态状态下的低He/热通量比并不反映地壳或地幔原始储层的He亏缺，而是空气饱和水、平流、传导和扩散的综合影响。与其他稀有气体测量和确定的稀有气体温度（NGTs）一起，拟议工作的第一部分将利用这些最近的发现来测试和开发新创建的He/热通量示踪剂，以确定大陆地区，特别是密歇根盆地的构造热事件在时间和空间上的发生。第二部分将利用常用工具来解决与冰覆盖地区NGT测定有关的问题。后者是地下水在渗透过程中与大气平衡的温度的直接测量，并提供了一个独特的机会来提高我们对大陆地区过去气候的理解，以及评估冰川作用对中高纬度地区地下水补给的影响。除了说明如何将氦/热通量比与NGT结合使用来研究大陆地区的构造热历史外，这项工作还将有助于提高对冰覆盖地区NGT测定的理解。这项工作将对地幔地球化学、地球物理学、构造地质学、水文学和古气候学等领域的知识产生影响。这项研究将成为一门全新的、完全以研究为导向的本科课程的基础。识别要解决的问题，收集和分析数据，测试假设，得出潜在的结论和撰写科学论文的原型将是本课程的组成部分。特别重要的是，非科学专业的本科生，特别是女性和代表性不足的群体参与科学发现，这有望吸引学生，并最终吸引越来越多的人进入科学事业。

For over two decades it has been assumed that transport properties for both heat and helium are similar in the crust and that transport for both tracers is in steady-state. In addition, the presence of a terrestrial helium-heat imbalance was suggested based on the observed low mantle He/heat flux ratio at the proximity of mid-ocean ridges. Recent work, however, indicates that the driving transport mechanisms for these two tracers are of a fundamentally different nature for a high range of rock permeabilities in the crust. It was concluded that low He/heat flux ratios in a steady-state regime do not reflect a He deficit in the crust or mantle original reservoirs, but rather, the combined impact of air saturated water, advection, conduction, and diffusion. Together with other noble gas measurements and determined noble gas temperatures (NGTs), part I of the proposed work will take advantage of these recent findings to test and develop the newly created He/heat flux tracer to identify the occurrence, both in time and space, of tectonothermal events in continental regions, and in the Michigan Basin in particular. Part II will take advantage of common tools in order to address questions in relation to NGT determination in ice-covered regions. The latter is a direct measure of the temperature at which groundwater equilibrated with the atmosphere during infiltration and offer a unique opportunity to improve our understanding of past climate in continental areas as well as to assess the impact of glaciation on groundwater recharge in mid-high latitude regions. In addition to illustrating how He/heat flux ratios can be used in conjunction with NGTs to investigate the tectonothermal history of continental regions, this work will also contribute to an improved understanding of NGT determination in ice-covered regions. This work will impact knowledge in the fields of Mantle Geochemistry, Geophysics, Structural Geology, Hydrology and Paleoclimatology.This research will be the basis of a new, exclusively research-oriented undergraduate course. Identifying problems to be addressed, collecting and analyzing data, testing hypotheses, reaching potential conclusions and writing the prototype of a scientific paper will be an integral part of this class. Of particular relevance is the participation of undergraduate non-science majors, in particular women and underrepresented groups into scientific discovery, which is expected to captivate students and ultimately draw increasing numbers into a scientific career.