CAREER: Evolution of the Southern African Plateau Using Advances in (U-Th)/He Thermochronometry, and Enhancing Student Critical Thinking in Science

南部非洲高原是大陆高原的一个独特和特别有趣的例子，大陆高原是大陆内部的一个大型高地。高原海拔上升的原因，无论是南部非洲高原和大陆高原一般，没有得到很好的理解。本项目利用磷灰石（U-Th）/He和4 He/3 He热年代学的最新进展研究了南部非洲高原的侵蚀历史。这些方法解决了岩石在地壳上部几公里处移动时的冷却历史，并允许深入了解地球表面的剥蚀和地形演变。侵蚀，或剥蚀，是地球表面的岩石材料的运输由一个移动的代理人，如水，风或冰。有两个主要的差距，我们的知识在南部非洲高原的侵蚀历史：高原本身的剥蚀历史是不好的约束，和后65 Ma的高原和沿海被动边缘的剥蚀历史是不为人所知。没有磷灰石（U-Th）/He数据已公布的任何地点在南非。该研究战略是专门设计的，以利用新的方法的进步，扩大了磷灰石（U-Th）/他和4 He/3 He技术的效用。四个研究问题的动机，并将解决本研究：1）是什么样的侵蚀历史的升高内部的南部非洲高原，它的影响是什么海拔增益高原？2)是否存在剥蚀的空间不均匀性，其模拟了岩浆活动、含金刚石管道就位和区域加热的空间扫描？3)区域性侵蚀是否可归因于高原内陆河流系统的演变？4)是否有一个阶段的加速侵蚀后，65马，可归因于一个阶段的高原表面隆起？正在开展一项全面的教育工作。项目人员正在与非洲地球观测网合作，在南非举办一个关于（铀-钍）/氦热测时学的短期课程，作为非洲地球观测网非洲范围网络计划的一部分。在非洲任何地方都没有（铀钍）/氦设施。一名与非洲地球观测站网络相关的非洲学生将参与该项目并前往美国，获得尖端分析方法的实践经验。首席研究员还参与了科罗拉多大学的科学教育计划，通过开发，实施和评估模块化方法来教授地球科学中的批判性思维。拟议的南非项目的研究动机将发展成为这些模块之一。新材料的有效性将在模块和课程水平上进行评估，并得到隶属于科罗拉多科学教育倡议的科学教学研究员的帮助。该项目得到了地球科学部的构造学和教育与人力资源计划以及NSF国际科学与工程办公室的非洲、近东和南亚计划的支持。

The southern African Plateau is a unique and particularly intriguing example of a continental plateau, a large elevated interior region of a continent. The causes of plateau elevation gain, both of the southern African plateau and of continental plateaus generally, are not well understood. In this project, recent advances in apatite (U-Th)/He and 4He/3He thermochronometry are used to investigate the erosional history of the southern African plateau. These methods resolve the cooling history of rocks as they move through the upper few kilometers of the Earth's crust, and allow insight into denudation and topographic evolution at the Earth's surface. Erosion, or denudation, is the transport of rock materials at the Earth's surface by a mobile agent, such as water, wind or ice.There are two major gaps in our knowledge of the erosional history of the southern African Plateau: the denudation history of the elevated plateau itself is poorly constrained, and the post-65 Ma denudation history of both plateau and coastal passive margins is not well known. No apatite (U-Th)/He data has been published for any location in South Africa. The research strategy is specifically designed to capitalize on new methodological advances that broaden the utility of the apatite (U-Th)/He and 4He/3He techniques. Four research questions motivate and will be addressed by the present study: 1) What is the erosional history of the elevated interior of the southern African plateau, and what are its implications for elevation gain of the plateau? 2) Is there a spatial heterogeneity of denudation that mimics the spatial sweep of magmatism, diamondiferous pipe emplacement, and regional heating across the region? 3) Is regional erosion instead attributable to the evolution of river systems in the plateau interior? 4) Is there a phase of accelerated erosion after 65 Ma that could be attributable to a phase of plateau surface uplift?A comprehensive education component is being carried out. Project personnel are collaborating with the African Earth Observatory Network to run a short course on (U-Th)/He thermochronometry in South Africa as part of African Earth Observatory Network's Africa-wide network plans. There is no (U-Th)/He facility anywhere in Africa. An African student associated with African Earth Observatory Network will be involved in the project and travel to the U.S. to gain hands-on experience with cutting-edge analytical methods. The principal investigator is also participating in the University of Colorado's Science Education Initiative through development, implementation, and evaluation of a modular approach to teaching critical thinking in Earth Science. The research motivations for the proposed South African project will be developed into one of these modules. The effectiveness of the new materials will be assessed at the module and course level with help from a Science Teaching Fellow affiliated with the Colorado's Science Education Initiative.This project is supported by the Tectonics and Education and Human Resources Programs in the Earth Sciences Division and the Africa, Near East & South Asia Program in NSF's Office of International Science and Engineering.