Collaborative Research: Evaluating Ancestry of the Tibet Plateau: Did a Mesozoic Proto-plateau Exist?

合作研究：评估青藏高原的祖先：中生代原始高原是否存在？

• 批准号: 1119219
• 负责人: Amy Weislogel
• 金额: $ 28.64万
• 依托单位: West Virginia University Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1119219&HistoricalAwards=false
• 关键词: Collaborative; Research; Evaluating; Ancestry; Tibet

Despite much investigation, when and how the Tibet plateau attained its elevation is a major unresolved problem in Earth science. This is partly due to the fact that early history of plateau growth is unknown. In recent years, many researchers have emphasized the effects of early Cenozoic India-Asia collision on the timing of increased elevation of the Tibet plateau; however, mechanical modeling of this increase in elevation requires improved constraints on the initial boundary conditions that existed prior to the impingement of India with Asia. This project employs a multi-disciplinary test of the hypothesis that a proto-plateau resulted from crustal thickening due to Mesozoic continent-continent collisional systems along the Qiangtang terrane borderlands prior to the collision of India with Asia. Reconstructing the upper crustal configuration of eastern Tibet prior to the Indian collision is performed using methods in sedimentology, stratigraphy, structure, stable isotope paleoaltimetry, geochemistry, geochronology, and basin modeling of the Mesozoic Qamdo basin in southeastern Tibet. Investigations of paleoenvironmental data from study of sedimentary deposits reveal patterns of aridification to compare with those indicative of plateau development. Comparison of sedimentary provenance of Qamdo basin deposits with lithologies of surrounding structural highlands and the structural kinematic history of adjacent deformation belts is used to model tectonic evolution and surface configuration of the region. Oxygen isotopic composition of paleosol carbonates is employed to assess paleoelevation history of the area and detect possible episodes of plateau rise. Documenting this early history of Tibet plateau evolution is required to address several outstanding issues of scientific and societal importance. First, research results provide constraints on initial input parameters that will improve the calibration of mechanical models of plateau development, as well as the threshold conditions under which extrusion tectonism was later initiated in the region. Also, the geological history of the Tibet plateau is thought to be tightly linked to major changes in climate patterns and wholesale secular changes in ocean chemistry due to chemical influx from the rivers that drain the Tibet plateau. Because chemical erosion of rocks consumes carbon dioxide from the atmosphere, erosion of the widespread uplifted region of the Tibet plateau, enhanced by a monsoonal climate, is a potential driver of global cooling episodes. Finally, the plate tectonic processes that formed the Tibet region bear the most relevance to the plate tectonic processes operating today that control the distribution of major seismic, volcanic, and mass wasting (e.g., landslide) hazards around the globe, as highlighted by the 2008 Wenchuan earthquake centered on the eastern Tibet plateau margin. In addition to the scientific objectives of this project, it is supporting the training of two Ph.D. students and three undergraduate students in a STEM discipline. Scientific collaboration between students and faculty at West Virginia University (U.S.), the University of Alabama (U.S.), and Nanjing University (China), is an important component of this project.

尽管进行了大量的研究，但西藏高原何时以及如何上升是地球科学中尚未解决的一个重大问题。这部分是由于高原生长的早期历史是未知的。近年来，许多研究者强调了新生代早期印度-亚洲碰撞对青藏高原海拔上升时间的影响;然而，这种海拔上升的力学模型需要改进印度与亚洲碰撞之前存在的初始边界条件的约束。该项目采用了多学科的假设，原始高原是由于地壳增厚，由于沿着羌塘-羌塘边界的大陆碰撞系统之前，印度与亚洲碰撞。利用沉积学、地层学、构造学、稳定同位素古高度学、地球化学、年代学和盆地模拟等方法，对青藏高原东部地区在印度碰撞前的上地壳结构进行了重建。通过对沉积沉积物的古环境数据的研究，揭示了干旱化的模式，并与高原发展的指示模式进行了比较。通过昌都盆地沉积物源与周边构造高地岩性及相邻变形带构造运动史的对比，模拟了昌都地区的构造演化和地表形态。古土壤碳酸盐的氧同位素组成被用来评估该地区的古海拔历史，并检测可能的高原上升事件。记录西藏高原演化的早期历史需要解决几个具有科学和社会重要性的突出问题。首先，研究结果提供了初始输入参数的限制，这将改善高原发展的力学模型的校准，以及挤压构造作用后来在该地区启动的阈值条件。此外，西藏高原的地质历史被认为与气候模式的重大变化和海洋化学的大规模长期变化密切相关，这些变化是由于西藏高原的河流流入的化学物质造成的。由于岩石的化学侵蚀会消耗大气中的二氧化碳，青藏高原广泛隆起地区的侵蚀，加上季风气候的增强，是全球变冷的潜在驱动力。最后，形成西藏地区的板块构造过程与今天的板块构造过程最相关，这些板块构造过程控制着主要地震、火山和质量浪费的分布（例如，全球地球仪的滑坡）灾害，如2008年以西藏高原东部边缘为中心的汶川地震所强调的。除了该项目的科学目标外，它还支持培养两名博士。学生和三名本科生在STEM学科。西弗吉尼亚大学（美国）学生和教师之间的科学合作，美国亚拉巴马大学，和南京大学（中国），是这个项目的一个重要组成部分。