Collaborative Research: Punctuated versus gradual topographic evolution of Cordilleran-style orogenic belts

长期以来，研究人员一直在争论像内华达山脉、喀斯喀特山脉和巴塔哥尼亚安第斯山脉这样的大型科迪勒山脉是如何随着时间的推移而发展的。特别是，两种主流理论解释了山带是如何随着海洋地壳在大陆地壳下的俯冲而演化的。这些理论认为，要么是长期的造山运动，要么是由于俯冲弧下地壳的缩短和岩石圈的移动，地形反复起伏的偶发模型。南巴塔哥尼亚安第斯山脉为评估经典科迪勒拉造山带长期地形变化的驱动因素提供了一个天然实验室。这项研究旨在量化南巴塔哥尼亚安第斯山脉在过去1亿年的海拔历史，以测试这些与科迪勒拉山脉建造有关的相互竞争的理论。研究结果将提高对俯冲过程如何塑造地球表面的理解，并将对理解当前和过去的地震活动、危险和资源具有广泛的意义。此外，对古代环境变化的洞察将揭示数百万年来大型山带的进化如何影响动植物。耶鲁大学皮博迪博物馆的一项新的增强现实展览将使无数游客能够虚拟地探索山脉如何影响降水，并说明大气过程和地形学中的重要概念。其他重要的社会成果包括为早期职业教师研究人员提供支持，并通过研究生和本科生招聘扩大对重要STEM学科的参与。关于间断造山运动和稳定造山运动的争论已经持续了很长时间。特别是，两种相反的观点认为，要么是持久的造山作用，要么是幕式的“科迪勒拉旋回”，在这种旋回中，由于地壳缩短和亚弧岩石圈的对流移动，地形反复起伏。大的科迪勒造山带（如内华达山脉、喀斯喀特山脉、南安第斯山脉）都有大量的花岗岩岩基，这些岩基是由弧下地幔的部分熔融和硅熔体通过上地壳的迁移形成的。该项目探讨了花岗岩基岩的侵位是巴塔哥尼亚安第斯山脉和其他科迪勒山脉造山带地形的主要驱动力。这项工作将重建白垩纪到最近巴塔哥尼亚安第斯山脉迎风和背风侧古降水的稳定同位素组成，以测试有关科迪勒拉式造山带形成的相互竞争的假设。在白垩纪至近代的几个沉积盆地中，对火山玻璃、土壤碳酸盐和沉积叶蜡进行了采样，重建了降水三角洲和三角洲18o。同位素数据将与具有高分辨率水同位素场的数值大气物理模型相结合，以约束巴塔哥尼亚安第斯山脉地形变化的时间和空间异质性。同位素支持的数值模型处理了观测到的气流行为的复杂性，并在造山带尺度上对降水同位素的现代分布进行了真实的描述。这种方法可以分离气候和地形对降水同位素的影响，更准确地重建地形变化。

Researchers have long debated how large Cordilleran orogens such as the Sierra Nevada, Cascades and Patagonian Andes develop through time. In particular, two dominant theories have emerged that explain how mountain belts evolve in response to subduction of oceanic crust beneath continental crust. These theories argue for either protracted mountain building, or an episodic model in which topography repeatedly rises and falls due to crustal shortening and removal of lithosphere beneath a subducting arc. The southern Patagonian Andes provides a natural laboratory for evaluating the drivers of long-term topographic change in a classic Cordilleran Orogen. This study aims to quantify the elevation history of the Southern Patagonia Andes for the last 100 million years to test these competing theories for Cordilleran mountain building. Results will improve understanding about how subduction processes shape the Earth's surface and will have broad implications for understanding current and past seismic activity, hazards, and resources. In addition, insight into changes in the ancient environment will shed light on how evolution of large mountain belts influences plants and animals over millions of years. A new Augmented Reality exhibit at the Yale University Peabody Museum will enable countless visitors to virtually explore how mountains influence precipitation and illustrate important concepts in atmospheric processes and geomorphology. Other important societal outcomes include providing support for an early career faculty researcher and broadening participation in an important STEM discipline through graduate and undergraduate recruiting.There has been a long debate about punctuated versus steady orogeny. In particular, two opposing ideas argue for either protracted orogenesis or an episodic "Cordilleran cycle" in which topography repeatedly rises and falls due to crustal shortening and convective removal of sub-arc lithosphere. The large Cordilleran orogens (e.g. Sierra Nevada, Cascades, Southern Andes) all host massive granitic batholiths that formed from the partial melting of the sub-arc mantle and the migration of silicic melts through the upper crust. This project explores the idea that emplacement of granitic batholiths was the primary driver of topography in the Patagonian Andes and other Cordilleran orogens. The proposed work will reconstruct the Cretaceous to recent stable isotopic composition of paleoprecipitation on the windward and leeward side of the Patagonian Andes to test competing hypotheses for the formation of Cordilleran-style orogens. Volcanic glasses, soil carbonates and sedimentary leaf waxes from several well-dated Cretaceous to recent sedimentary basins will be sampled to reconstruct precipitation deltaD and delta18O. Isotope data will be coupled with a numerical atmospheric physics model with high-resolution water isotope fields to constrain the timing and spatial heterogeneity of topographic change in the Patagonian Andes. The isotope-enabled numerical model deals with observed complexities in the behavior of airflow and produces realistic representation of modern distribution of precipitation isotopes on the scale of an orogen. This approach enables separation of climatic and topographic effects on precipitation isotopes and more accurate reconstructions of topographic change.