TIMING OF COOLING AND EXHUMATION OF LARAMIDE UPLIFTS INFORMS MODELS OF FLAT-SLAB SUBDUCTION

该项目旨在确定共同构成美国西部内陆落基山脉的主要山脉的隆起年龄。这些山脉在地质文献中被称为“拉腊米隆起”，以怀俄明州的拉勒米市和县命名，拉腊米位于这些隆起明显发育的地区。拉腊米山脉隆起的时间尚不清楚，但对于评估东太平洋盆地和北美板块西部地区构造板块的形状和运动方向至关重要。这项工作对公众很重要，原因有几个：（a）落基山脉是西部山区的决定性景观，200多年来一直激励着作家，艺术家，企业家，移民和科学家;然而，地质学家之间没有达成共识来解释这些山脉的起源。(b)由于其高海拔和南北方向，这一壮观的景观影响了整个美国的生态和气候。（c）拉腊米德地区对美国具有巨大的经济重要性，拥有重要的地下水、矿产和碳氢化合物资源。(d)虽然Laramide隆起不再“活跃”，但该项目的结果将有助于了解今天地球上类似构造过程仍然活跃的地区（例如，南美洲西部和阿拉斯加南部）的地震危险。最后，一组本科生和研究生将在本项目的范围内接受培训，本项目的主要目标是确定蒙大拿州、怀俄明州和犹他州的Laramide隆起的挖掘时间。这是必不可少的通知构造和地球动力学模型的Laramide造山带，这通常是由于平板俯冲。这种模型在很大程度上依赖于Laramide隆起的时空模式。大洋高原和海隆的板块俯冲是会聚边缘的重要地球动力学现象，与区域高原隆升、弧岩浆活动的终止和上覆板块的地震活动有关。该项目将采用多成分测年法，包括磷灰石裂变径迹和（U-Th-Sm）/He热年代学，当结合热动力学建模和沉积记录时，将限制Laramide地区的冷却和侵蚀历史。隆起事件的时间和分布的区域模式将为美国西部的板块构造模型提供限制。这项研究所获得的知识将可输出到其他活跃和古老的平板构造系统，如阿拉斯加南部，该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的评估被认为值得支持。影响审查标准。

This project intends to determine the ages of uplift of the major mountain ranges that together constitute the Rocky Mountains of the western interior United States. These ranges are referred to in the geological literature as "Laramide uplifts", after the city and county of Laramie, Wyoming, which is situated in the region where these uplifts are notably developed. The timing of uplift of the Laramide ranges is poorly understood, but critical for assessing the shape and movement direction of tectonic plates in the eastern Pacific basin and western regions of the North American plate. This work is important to the public for several reasons: (a) The Rocky Mountains are the definitive landscape of the mountain west, a landscape that has inspired writers, artists, entrepreneurs, emigrants, and scientists for more than 200 years; yet, no consensus exists among geologists to explain the origins of these mountains. (b) By virtue of its high elevation and north-south orientation, this spectacular landscape impacts the ecology and climate of the entire U.S. (c) The Laramide region is of enormous economic importance to the U.S., containing strategically important groundwater, mineral, and hydrocarbon resources. (d) Although the Laramide uplifts are no longer "active", results of this project will useful for understanding seismic hazards in regions on Earth today where similar tectonic processes are still active (for example, western South America and southern Alaska). Finally, a group of undergraduate and graduate students will be trained in the context of this project.The primary objective of this project is to determine the timing of exhumation of Laramide uplifts in Montana, Wyoming and Utah. This is essential to inform tectonic and geodynamic models of the Laramide orogeny, which is generally attributed to flat-slab subduction. Such models rely heavily on spatio-temporal patterns of Laramide uplift. Flat-slab subduction of oceanic plateaus and aseismic ridges are important geodynamic phenomena in convergent margins, with respect to regional plateau uplift, termination of arc magmatism, and active seismicity in the overriding plate. This project will apply a multi-component dating approach, including apatite fission track and (U-Th-Sm)/He thermochronology, which, when combined with thermo-kinematic modeling and the record of sedimentation, will constrain the cooling and erosion histories of the Laramide region. Regional patterns in timing and distribution of uplift events will provide constraints for plate tectonic models of the western U.S. Knowledge gained by this research will be exportable to other active and ancient flat-slab tectonic systems such as southern Alaska, Central America and western Argentina.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.