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

蒙古的阿拉泰山脉是蒙古西部的一条大约2000公里长的山脉，是中亚被称为中亚造山带的广大山区的一部分。了解距离最初形成的现代构造板块边界1000公里的山系是如何形成的，因为阿拉泰山脉在调节亚洲气候和生物多样性以及通过侵蚀和泥沙输送控制地球物质的分布和重组方面发挥了重要作用。这项研究将测试地壳如何在构造板块的中央而不是边缘变形为山脉。PIS将使用热年代学(矿物冷却历史研究)来衡量山脉发展的时间，并对沉积岩进行实地研究，以研究山脉隆起造成的侵蚀和沉积模式的变化。这些结果将与测试构造板块中央形成山脉的不同方式的数值模型进行比较。这项研究将通过以下方面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族裔和代表性不足的学生；2)增加妇女作为首席研究员和该项目的研究生在STEM中的参与；3)通过本科教育和教育推广，提高公众的科学素养；4)发展美国和蒙古科学家之间的伙伴关系；以及5)开发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，这些过程定义了地形地貌。然而，我们对板块内部造山作用的理解发展较少，因为陆内造山带无视造山作用作为板块边界驱动过程的模型。蒙古阿拉泰山脉是最大的陆内造山系之一-中亚造山带的一部分，但解释这一山系起源的资料有限。该项目将测试蒙古阿拉泰陆内造山作用的特定模式，每种模式都预测了不同的隆升时间、速度和方式。这项研究将结合基岩和碎屑岩的热年代学、沉积学和盆地分析以及地质力学模拟来记录蒙古阿拉泰陆内造山作用的开始时间；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、继承性)；以及了解板块边界力产生陆内变形的可能条件和这种变形发生的时间尺度。这些结果将检验蒙古阿拉泰是来自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观测，以检验这些假设，这些假设可以进一步受到数值模型的约束，这些模型询问这些过程的地质力学合理性。这项研究不仅将提供蒙古阿拉泰境内沿走向带800公里范围内的第一个基底热年代学数据集和整个阿拉泰系统(2000公里走向长度)的第一个碎屑岩热年代学数据集，而且还将把该数据集与同期沉积盆地的工作和地质力学模拟相结合，将这些数据置于严格约束的地质背景中。这项拟议的研究还将提高我们对全球陆内造山带形成过程的理解，这是构造领域的一个主要悬而未决的问题。该项目由地球科学部门的构造计划和既定的刺激竞争研究计划(EPSCoR)联合资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Mongolian Altai are an approximately 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 project is jointly funded by the Tectonics program in the division of Earth Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).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.