Collaborative Research: How and when did the Mongolian Altai (de-)form? Implications for intracontinental deformation

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。蒙古阿尔泰山脉是蒙古西部约2000公里长的山脉，是中亚广阔山区的一部分，被称为中亚造山带。了解一个距离现代构造板块边界1000公里的山脉系统是如何形成的是很重要的，因为阿尔泰在调节亚洲气候和生物多样性以及通过侵蚀和沉积物运输控制地球物质的分布和重组方面发挥着重要作用。这项研究将测试地壳是如何在构造板块的中间而不是边缘变形成山脉的。pi将使用热年代学（对矿物冷却历史的研究）来测量山区发展的时间，并对沉积岩进行实地研究，以研究由山区隆起引起的侵蚀和沉积模式的变化。这些结果将与在构造板块中间测试不同方式形成山脉的数值模型进行比较。该研究将通过以下方式提供重要的社会成果：1)支持STEM领域的研究生和本科生的培训，包括西班牙裔服务机构的少数民族和代表性不足的学生；2)在该项目中增加女性作为主要研究人员和研究生参与STEM； 3)通过本科教育和教育推广提高公众科学素养。4)发展美国和蒙古科学家之间的伙伴关系，5)发展本科教育的在线互动实地考察。最近的大型跨学科项目使我们对定义地形景观的构造板块边缘过程的速率、相对时间和周期性的理解取得了重大进展。然而，我们对板块内部造山作用的理解尚不成熟，因为大陆内造山作用不符合板块边界驱动造山作用的模式。蒙古阿尔泰山脉是世界上最大的陆内造山带之一——中亚造山带的一部分，但目前还没有足够的资料来解释这个山系的起源。该项目将测试蒙古阿尔泰大陆内造山作用的特定模型，每个模型预测不同的时间、速率和隆升风格。本研究将结合基岩和碎屑热年代学、沉积学和盆地学分析以及地质力学模拟，记录蒙古阿尔泰陆内造山运动的开始时间；了解该地区地形景观形成的基本控制因素（流变学、地球动力学、遗传）；并了解由板块边界力产生大陆内变形的可能条件以及这种变形发生的时间尺度。这些结果将有助于测试蒙古阿尔泰是否是中生代缝合带的残余地形，是均衡或动态过程的地球动力学特征，还是由于新生代板块边界应力的局部变形而形成的。现场和分析数据将提供直接的观察结果来验证这些假设，这些假设可以进一步受到质疑这些过程的地质力学合理性的数值模型的约束。这项研究不仅将提供蒙古阿尔泰地区800公里走向带的第一个基底热年代学数据和整个阿尔泰系统（2000公里走向长度）的第一个碎屑热年代学数据，而且将这些数据与同期沉积盆地和地质力学建模的工作相结合，将这些数据置于良好的地质约束背景下。该研究还将提高我们对全球陆内造山带形成过程的理解，这是构造学领域的一个主要悬而未决的问题。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The Mongolian Altai are a ~2000 km-long mountain range in western Mongolia that are part of a vast mountainous region in central Asia referred to as the Central Asian Orogenic Belt. Understanding how a mountain system that is located 1000 km from a modern tectonic plate boundary originally formed is important as the Altai play an important role in regulating Asian climate and biodiversity and in controlling the distribution and reorganization of Earth materials through erosion and sediment transport. This study will test how the Earth’s crust deforms into mountains in the middle of tectonic plates rather than at the edges. The PIs will use thermochronology (the study of mineral cooling histories) to measure the timing of mountain development and conduct field-based studies of sedimentary rocks to study changes in erosion and deposition patterns caused by mountain uplift. These results will be compared to numerical models testing different ways to form mountains in the middle of tectonic plates. This research will provide important societal outcomes by 1) supporting the training of graduate and undergraduate students in STEM fields including minority and underrepresented students at a Hispanic Serving Institution, 2) increasing participation of women in STEM as both Principal Investigators and graduate students within this project, 3) increasing public scientific literacy through undergraduate education and education outreach, 4) developing partnerships between American and Mongolian scientists, and 5) the development of online interactive field tours for undergraduate education. Recent large-scale, interdisciplinary projects have led to major advances in our understanding of the rates, relative timing, and periodicity of tectonic plate margin processes that define orographic landscapes. However, our understanding of plate interior orogenesis is less evolved, as intracontinental orogens defy models of orogenesis as a plate-boundary driven process. The Mongolian Altai are part of one of the largest intracontinental orogenic systems–the Central Asian Orogenic Belt, and yet limited data exist to explain the origin of this mountain system. This project will test specific models of intracontinental orogenesis in the Mongolia Altai, each of which predict a different timing, rate, and style of uplift. This research will integrate bedrock and detrital thermochronology, sedimentology and basin analysis, and geomechanical modeling to document the timing of onset of intracontinental orogenesis in the Mongolian Altai; understand fundamental (rheological, geodynamic, inherited) controls on the formation of an orographic landscape in this region; and to understand the possible conditions that produce intracontinental deformation from plate boundary forces and the timescales on which this deformation occurs. These outcomes will allow testing of whether the Mongolian Altai are relict topography from a Mesozoic suture zone, are a geodynamic feature of isostatic or dynamic processes, or formed due to localized deformation from Cenozoic plate boundary stresses. Field and analytical data will provide direct observations to test these hypotheses that can be further constrained by numerical models that interrogate the geomechanical plausibility of these processes. This study will not only provide the first basement thermochronologic dataset from a ~800 km along strike zone within the Mongolian Altai and the first detrital thermochronologic dataset from the entire Altai system (2000 km strike length), but will integrate this dataset with work in contemporaneous sedimentary basins and geomechanical modeling to put these data in a well-constrained geologic context. The proposed research will also improve our understanding of what processes drive formation of intracontinental orogens globally, a major outstanding question in the field of tectonics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.