Lithospheric Dripping in Central Tibet: Underappreciated Factor in Orogenic Plateau Development?

西藏中部岩石圈滴水：造山高原发育过程中被低估的因素？

• 批准号: 2048656
• 负责人: Paul Kapp
• 金额: $ 44.32万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-15 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048656&HistoricalAwards=false
• 关键词: Lithospheric; Dripping; Central; Tibet; Underappreciated

The lower part of a continental plate is more dense than underlying asthenosphere. If it gets thickened as a result of plate convergence, such as within the India-Asia collision zone, it may become gravitationally unstable and sink into the deeper mantle as a large sheet or smaller-sized drips. This project will test the hypothesis that 45-20 million year old elliptical-shaped basins in central Tibet formed above sinking lithospheric drips, while mantle-derived volcanic rocks simultaneously erupted along the basin-bounding topographic bulges. If validated, the lithospheric drip theory would provide an appealing mechanism to explain the multitude of enigmatic elliptical basins found in all of Earth’s major orogenic plateaus. In collaboration with the University of Arizona’s Assistant Dean of Military and Veteran Engagement, this project will engage three undergraduate-student veterans in geological field and laboratory research. Military veterans are returning from active duty to college in increasing numbers and are underrepresented in the Science-Technology-Engineering-Math workforce. The effectiveness of the student-veteran engagement program will be assessed, along with which factors influence veteran career pathways, by delivering entrance and exit surveys. The project will also train two graduate students and facilitate continued academic, scientific, and cultural exchange among people and institutions in the United States, China, and Tibet.In addition to the lithospheric drip theory, the project will test the alternative hypotheses that Cenozoic shortening, volcanism, and basin formation in central Tibet are manifestations of (i) southward propagation of regional (600 km long) thrust systems and lithospheric thickening followed by lithospheric root removal or (ii) long-lived (active from Eocene through early Miocene time) ~200-250-km-long thrust belts and associated flexural loading across central Tibet, with unrelated mantle processes generating localized volcanic highlands. The hypotheses make distinct predictions about the temporal-spatial distribution of shortening, age of shortened basin fill relative to the age of adjacent volcanic rocks, basin geometries and the nature of their margins, and sedimentary provenance and dispersal patterns. A combination of geological mapping, basin analysis, structural analysis and restorations, and U-Pb igneous and detrital zircon geochronology will be employed to test these predictions. Field research will include the principal investigators, graduate students, undergraduate student-veterans, and collaborators from the Institute of Tibetan Plateau Research in Beijing, and will focus on Cenozoic geology within and between three basins in central Tibet. The spatial coverage will permit assessment of whether (i) shortening structures are localized to the basins or extend regionally along strike, (ii) the basins were previously integrated as long and narrow E-W or more regional basins, or developed throughout their history as isolated depocenters, and (iii) maximum basin subsidence and shortening were coeval with eruption of adjacent volcanic rocks. Ultimately, insofar as Tibet is the world’s archetypical collisional plateau, project results will have relevance for other orogenic plateaus worldwide.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.

连续板的下部比下层下层更致密。如果由于板收敛而变厚，例如在印度 - 亚洲碰撞区内，它可能会在重力上不稳定并沉入更深的地幔中，因为大小或较小的滴水。该项目将检验以下假设：在下沉的岩石圈下方形成的中部西藏中有45-20万年历史的椭圆形低音，而地幔衍生的火山岩只是沿着盆地的地形凸起爆发。如果经过验证，岩石圈驱动理论将提供一种外观机制，以解释地球所有主要山地造型高原中发现的许多神秘的椭圆鲈。该项目与亚利桑那大学军事和退伍军人参与的助理院长合作，将在地质领域和实验室研究中与三名本科生的退伍军人互动。军人退伍军人的数量越来越多，在科学技术工程学报的劳动力中的人数不足。通过进行入学和退出调查，将评估学生参与计划的有效性，以及哪些因素影响退伍军人职业道路。 The project will also train two graduate students and facilitated continued academic, scientific, and cultural exchange among people and institutions in the United States, China, and Tibet.In addition to the lithosphere drill theory, the project will test the alternative hypotheses that Cenozoic shortening, volcanism, and basin formation in central Tibet are manifestations of (i) southward propagation of regional (600 km long) thrust systems and lithosphere增厚，然后是岩石圈根的去除或（ii）长寿命（从始新世到中新世早期的活性）〜200-250 km长的推力带，并在西藏中部中央横跨中央的柔性载荷，并产生无关的地幔过程，产生了局部的火山高地。这些假设对相对于相邻火山岩的年龄，盆地几何形状及其边缘的性质以及沉积物来源和分散模式相对于相对于相邻火山岩的年龄的缩短盆地填充年龄的临时空间分布做出了不同的预测。将聘请地质映射，盆地分析，结构分析和修复体以及U-PB火成岩和碎屑锆石地质学的结合来测试这些预测。现场研究将包括北京藏族高原研究所的主要研究人员，研究生，本科生和合作者，并将重点关注西藏中部三个贝斯之间的新生代地质。空间覆盖范围将允许评估（i）缩短结构是否位于贝司或沿罢工区域延伸，（ii）先前将贝斯整合为长而狭窄的E-W或更多区域贝斯，还是在整个历史中作为孤立的储户发展，（III）盆地的繁殖和最大的盆地和近亲与邻近落叶岩的喷发相同。最终，只要西藏是世界上古老的高原，项目结果将与全球其他造口型平台有关。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响标准来评估通过评估来诚实地支持支持。

项目成果

Timing and mechanisms of Tibetan Plateau uplift

• DOI: 10.1038/s43017-022-00318-4
• 发表时间: 2022-07-28
• 期刊: NATURE REVIEWS EARTH & ENVIRONMENT
• 影响因子: 42.1
• 作者: Ding, Lin;Kapp, Paul;Wang, Chao
• 通讯作者: Wang, Chao

Where did the Arizona‐Plano Go? Protracted Thinning Via Upper‐ to Lower‐Crustal Processes

• DOI: 10.1029/2021jb023850
• 发表时间: 2022-03
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: G. Jepson;B. Carrapa;S. George;L. Reeher;P. Kapp;G. Davis;S. Thomson;C. Amadori;C. Clinkscales;Sean Jones;A. Gleadow;B. Kohn