Collaborative Research: Testing Models of Tibetan Plateau Uplift Using Stable Isotope-Based Paleoaltimetry

青藏高原的隆升历史是区分印度-亚洲陆-陆碰撞系统应变调节模式的几种直接方法之一。此外，喜马拉雅山和西藏的古地形演变在大气动力学中发挥着重要作用，该地区的侵蚀影响了大气和海洋化学。 喜马拉雅山和西藏的海拔历史数据约束可以发挥关键作用，在确定各种机制，包括地壳俯冲，地壳增厚，地壳和地幔岩石圈增厚，随后对流去除地幔岩石圈，以及逃逸和挤出的程度，有助于整个地区的高海拔和应变分布。我们目前的结果，我们以前的调查喜马拉雅山和西藏古高程。一个积极的新项目计划解决西藏高原古海拔历史的其他方面。我们现有的西藏南部和中部的数据表明，西藏和喜马拉雅山已经达到了目前的地位，在这些地区的时间之前，迄今为止收集的最古老的样品，每个地区没有证据表明，在海拔变化与对流不稳定加厚岩石圈地幔根。该建议寻求支持，特别关注较老的部分，以确定我们是否可以捕捉到西藏南部和中部各地区的实际隆起，重要的是确定碰撞前的地形，这是印度-亚洲碰撞期间地壳质量平衡和应变调节的所有模型的重要边界条件。现有的解释碰撞前的亚洲边缘作为安第斯型边缘往往被认为意味着边缘有一个碰撞前的地形可比的安第斯山脉。我们建议明确测试这一假设广泛采样的古土壤碳酸盐夹层内的林子忠火山岩的晚白垩世至始新世的年龄从众多保存的部分延伸到东部的Oiyug在西部的Markam。此外，我们建议采样古土壤和湖相碳酸盐岩从始新世到渐新世火山岩和山间盆地序列也分布在西藏南部和中部。该项目的智力价值包括我们的研究在确定青藏高原南部高地形发展的初始年龄方面的潜力，以及为西藏-喜马拉雅造山带应变适应模型提供时间和空间的古高程限制。 该研究的更广泛的影响包括对大陆碰撞有更好和更全面的了解，此外，与我们的中国合作者进行数据，研究方法和关于西藏构造演化的解释的跨文化交流，以及该项目为芝加哥大学和迈阿密大学的研究生提供的研究机会。

The elevation history of the Tibetan Plateau is one of the few direct ways of discriminating among models for the modes of strain accommodation in the India-Asia continent-continent collision system. In addition, the paleo-topographic evolution of the Himalayas and Tibet play important roles in the dynamics of the atmosphere and erosion from this region has been implicated in affecting atmospheric and ocean chemistry. Data constraining the elevation history of the Himalaya and Tibet can play a critical role in determining the degree to which various mechanisms, including crustal subduction, crustal thickening, crust and mantle-lithosphere thickening with subsequent convective removal of the mantle lithosphere, as well as escape and extrusion have contributed to the high elevation and distribution of strain across this region. We present results of our previous investigations of Himalaya and Tibetan paleoaltimetry. An aggressive new program is planned to address additional facets of the paleo-elevation history of the Tibetan Plateau. Our existing data from southern and central Tibet indicate that Tibet and Himalayas had already achieved its current stature in each of those areas at times prior to the oldest samples thus far collected and that each of the areas shows no evidence for changes in elevation associated with convective destabilization of a thickened lithospheric mantle root. This proposal seeks support to specifically focus on older sections in order to determine whether we can capture the actual uplift of various parts of southern and central Tibet, and importantly to determine the pre-collisional topography which is an important boundary condition for all models of crustal mass balance and strain accommodation during the India-Asia collision. Existing interpretation of the pre-collisional Asian margin as an Andean-type margin are often taken to imply that the margin had a pre-collisional topography comparable to the Andes. We propose to explicitly test this hypothesis by extensively sampling the paleosol carbonates interbedded within the Linzizhong Volcanics of Late Cretaceous to Eocene age from numerous preserved sections extending from Oiyug in the west to Markam in the east. In addition, we propose to sample paleosol and lacustrine carbonates from Eocene to Oligocene volcaniclastic and intermontane basin sequences also distributed across southern and central Tibet. The intellectual merits of the project include the potential our research has in identifying the initial age of the development of high topography in the southern Tibetan plateau, as well as providing temporal and spatial paleo-elevation constraints for models of strain accommodation in the Tibetan-Himalayan orogen. The broader impacts of the study include developing a better and more general understanding of continental collisions, and in addition, the cross-cultural exchange of data, research methods, and interpretations regarding the tectonic evolution of Tibet with our Chinese collaborators, as well as the research opportunity the project provides for graduate students at both the University of Chicago and Miami University.