From subduction to sand: Quantifying the balance between tectonic and surface processes during early continental collision and UHP rock exhumation

地球上许多伟大的山脉，如阿尔卑斯山和喜马拉雅山脉，都是两块大陆碰撞的结果。当山脉被构造力推高时，它们也会被地表侵蚀所磨损。地形抬升引起长期的区域和全球气候变化，反过来，气候变化也与构造过程速率的变化有关。该项目将通过综合利用最先进的数值模拟和分析技术，确定和量化山隆起早期阶段生长和侵蚀之间的竞争。在大陆碰撞的早期阶段，不寻常的（和诊断的）岩石类型在非常高的压力条件下形成。这些岩石中的某些矿物质保存了从地幔深处最初形成，到随后被运送到地球表面，再到被侵蚀，最后以沙粒的形式沉积在沉积岩中的过程中所经历的压力和温度的细节。这些矿物保留了独特的化学特征，这使得它们与其他岩石类型中的矿物区别开来，即使它们被侵蚀变成了沙子。沙粒不仅保留了原始岩石类型的信息，还保留了原始岩石形成和运输历史的细节。因此，与目前保存在基岩记录中的信息相比，解开这些信息将使我们更深入地了解山带生长历史的早期阶段。然而，破译这些细节所需的方法目前还不够精确，无法对构造或侵蚀过程的变化速率或模型的约束条件提供有用的见解。因此，该项目还将开发和利用创新技术，从这些高压岩石及其侵蚀残留物中获取高精度数据。这些数据将使在形成的早期阶段形成山带的相互竞争的力量得以量化，并使数值模型得到有力的检验。该建议的独特贡献在于将地球动力学数值模拟与基于观测数据的研究相结合，从而利用这两个通常不同的领域之间的协同作用。

Many of the Earth's great mountain ranges, such as the Alps and the Himalaya, result from the collision between two continents. As mountains get pushed up by tectonic forces, they also get worn away by surface erosion. The uplift of topography causes long-term regional and global climate change, and conversely, changes in climate have also been linked to changes in the rate of tectonic processes. This project will define and quantify the competition between growth and erosion during the early stages of mountain uplift by exploiting a combination of state-of the art advances in numerical modelling and analytical techniques. During the early stages of continental collision, unusual (and diagnostic) rock types form under very high pressure conditions. Certain minerals in these rocks preserve details of the pressures and temperatures experienced during the journey from initial formation deep in the mantle, through their subsequent transport to the Earth's surface, their erosion, and their final deposition as sand grains in a sedimentary rock. The minerals retain distinctive chemical signatures which allows them to be distinguished from those formed in other rock types, even when eroded and turned into sand. Sand grains retain information about not only the original rock type, but also about details of the formation and transport history of the original rock. Unlocking this information will therefore yield insight into earlier stages of mountain belt growth history than is currently preserved in the bedrock record. However the methods needed to decipher these details are currently insufficiently precise to provide useful insight into changes in rates of tectonic or erosive processes, or constraints for the models. This project will therefore also develop and exploit innovative techniques for obtaining high-precision data from these high pressure rocks and their eroded remains. These data will enable the competing forces which act to shape a mountain belt during the early stages of formation to be quantified and allow the numerical models to be robustly tested. The unique contribution of this proposal lies in the combination of geodynamic numerical modelling with studies based on observational data and hence exploiting the synergy between these two, normally disparate, fields.