Collaborative Research: Basin Evolution and Elevation History of the SE Margin of the Tibetan Plateau: Constraints on the Timing and Mechanisms of Surface Uplift

合作研究：青藏高原东南缘盆地演化与高程历史：地表隆起时间与机制的制约

• 批准号: 1019762
• 负责人: Carmala Garzione
• 金额: $ 6.18万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1019762&HistoricalAwards=false
• 关键词: Collaborative; Research; Basin; Evolution; Elevation

The collision of India and Asia is the archetype of continent-continent collision in plate tectonics and is responsible for the development of the 5 km high Tibetan Plateau. Most of the Plateau?s margin is bounded by steep, fault-bounded topographic fronts (e.g. the Himalaya), yet the southeastern Plateau margin is a diffuse boundary with major faults that parallel the topographic gradient. A team of researchers from Syracuse University and the University of Rochester, in collaboration with scientists from the Chinese Institute for Tibetan Studies, will utilize sedimentary rocks preserved on the southeastern margin of the Tibetan Plateau to examine the history of regional drainage basin evolution and the formation of high topography in this area, located near Kunming, Yunnan Province, China. River sandstones are a mixture of sediment from erosional source regions upstream in a watershed. The range of crystallization age and thermal exhumation ages of the mineral zircon, found within sandstones, provides a fingerprint of the areas being eroded. Changes in the signature of zircon ages in sandstones of known depositional age will be used to trace the changes in sediment source as river networks eroded distinct bedrock source areas.Minerals and plant organic matter record information about earth?s surface conditions over the time in which they formed. The variation in the oxygen isotopic composition of meteoric (precipitation and surface) water is, in part, sensitive to elevation. The isotopic composition of meteoric water is recorded in mineral and plant material, and can be used to decipher the elevation of the ground surface where the plant grew and/or the minerals formed. The organic matter from soil microbes is distinct from that of plants, and the bond arrangement reflects soil temperature, another parameter sensitive to elevation. Over a vertical succession, sedimentary rocks containing appropriate material can be used to reconstruct how elevations changed over time. A principal goal of this research is to reconstruct the elevation history of the SE margin of the Tibetan Plateau over the past 40 million years. Elevation, a key geophysical parameter, is a critical constraint for unraveling the processes by which the earth?s crust evolves.This research will address a major outstanding question in continental tectonics: how do diffuse margins of plateaus form? One of the leading hypotheses for the formation of the southeastern Tibetan Plateau margin suggests that a weak, plastically deforming lower crust flows from the adjacent high Plateau toward the edges. By unraveling both the change in sediment sources and elevation history it will be possible to constrain the timing, rate and process by which this type of plateau margin develops, while at the same time testing the viability of the lower crustal flow hypothesis. The results of the study will have implications beyond continental tectonics, as it is hypothesized that the Tibetan Plateau has a major influence on global climate.This project is supported by the Tectonics Program in the Earth Sciences Division and the East Asia and Pacific Program in NSF's Office of International Science and Engineering.

印度和亚洲的碰撞是板块构造中大陆与大陆碰撞的原型，是导致5公里高的青藏高原形成的原因。高原边缘的大部分地区以陡峭、断层为界的地形前缘（例如喜马拉雅山）为界，但高原东南部边缘是一个弥漫的边界，有与地形梯度平行的主要断层。来自雪城大学和罗彻斯特大学的研究小组与中国西藏研究院的科学家合作，将利用青藏高原东南缘保存的沉积岩来研究区域流域演化和形成的历史该地区地势较高，位于中国云南省昆明市附近。河流砂岩是流域上游侵蚀源区沉积物的混合物。砂岩中发现的矿物锆石的结晶年龄和热折返年龄范围提供了被侵蚀区域的指纹。已知沉积年龄的砂岩中锆石年龄特征的变化将用于追踪河流网络侵蚀不同基岩源区时沉积物来源的变化。矿物和植物有机质记录了一段时间内地球表面状况的信息。他们形成了。大气（降水和地表）水氧同位素组成的变化在一定程度上对海拔高度敏感。大气水的同位素组成记录在矿物和植物材料中，可用于破译植物生长和/或矿物形成的地表海拔。土壤微生物的有机质与植物的有机质不同，键排列反映了土壤温度，这是另一个对海拔敏感的参数。在垂直序列中，含有适当材料的沉积岩可用于重建海拔随时间的变化。这项研究的主要目标是重建青藏高原东南边缘过去4000万年的海拔历史。海拔是一个关键的地球物理参数，是揭示地壳演化过程的关键约束。这项研究将解决大陆构造中的一个重大悬而未决的问题：高原的扩散边缘是如何形成的？关于青藏高原东南部边缘形成的主要假说之一表明，一个弱的、塑性变形的下地壳从邻近的高原流向边缘。通过揭示沉积物来源和海拔历史的变化，将有可能限制这种类型的高原边缘发展的时间、速率和过程，同时测试下地壳流假说的可行性。这项研究的结果将产生超越大陆构造的影响，因为假设青藏高原对全球气候有重大影响。该项目得到了地球科学部的构造计划和美国国家科学基金会的东亚和太平洋计划的支持国际科学与工程办公室。