Reconstructing the Late Cenozoic History of Surface Uplift and Climate Change in the Central Rocky Mountains

落基山脉是美国大陆内部的一个广阔的高海拔地区。今天，落基山脉中部的海拔高达海平面以上4公里，而盆地底部大多位于约1.5公里处。但8000万年前，整个地区都接近海平面。目前的高海拔在多大程度上是在最后一次造山运动（大约5000万年前结束的拉腊米造山运动）中产生的，或者是在最近的地表隆起过程中形成的，这是未知的。对比数据集，导致了两个学校的思想，在这一地区的高高原发展：构造解释主要集中在新近纪隆起，由于在地球活动的过程？虽然气候解释表明，该地区只发生了少量的隆起，但在过去几百万年里，该地区经历了由气候变化引起的大量侵蚀。该项目通过结合落基山脉中部和邻近大平原上新生代沉积岩的沉积学和稳定同位素地球化学，对这些解释提供了新的限制。这些数据澄清了盆地何时形成并随着时间的推移而整合，并允许重建过去几百万年的海拔和气候变化。这些数据限制了（1）盆地中河流沉积物和风沉积物变化的发生和时间，可能与区域气候变化有关;（2）通过重建火山玻璃和土壤以及湖泊碳酸盐的古水的氢氧同位素比率以及这些碳酸盐的聚集同位素的古空气温度来确定地表高程变化的时间。这些结果可以用来评估和完善中央落基山脉的形成机制，并帮助确定落基山脉是否最近获得了海拔或长期死亡的山脉。这项研究的更广泛的影响包括为女性助理教授提供早期职业支持。该研究还建立了一种创新方法，将三套稳定同位素数据与盆地沉积学相结合，提供了一种区分气候变化与地表隆起的手段。此外，这项研究与其他类似的，国家科学基金会支持的，研究计划，覆盖美国西部的其他地区整合描绘了整个地区的陆地表面最近的垂直运动的更广泛的图片。最后，这项研究的结果将被纳入一个电子演示文稿，将在怀俄明州校园的地质博物馆安装的一部分。该博物馆是来自全州的初中和高中班级的经常目的地，也是其他游客的停留地。本次演讲将提供深入了解整个国家和地区的高海拔的起源。

The Rocky Mountains are an extensive area of high elevation in the U.S. continental interior. Today, elevations in the central Rockies reach up to 4 kilometers above sea level, while basin floors mostly lie at about 1.5 kilometers. But 80 million years ago the entire region was near sea level. It is unlear to what extent present high elevations were generated during the last mountain-building event (the Laramide Orogeny, ending about 50 million years ago) or were formed during more recent surface uplift. Contrasting data sets have led to two schools of thought regarding high plateau development in this region: tectonic interpretations primarily focus on Neogene uplift due to processes active in the Earth?s upper mantle, while climatic interpretations suggest only a small amount of uplift has taken place, but instead the region has undergone a significant amount of erosion caused by climate change during the last few million years. This project provides new constraints on these interpretations by combining sedimentology and stable isotope geochemistry of upper Cenozoic sedimentary rocks in the central Rockies and adjacent Great Plains. These data clarify when the basins formed and were integrated through time, as well as allow reconstruction of changes in elevation and climate during the last few million years. These data constrain (1) the occurrence and timing of a change from river-laid to wind-laid deposits in the basins, possibly related to regional changes in climate; and (2) the timing of surface elevation changes by reconstructing the hydrogen and oxygen isotope ratios of ancient water from volcanic glass and soil and lake carbonates and ancient air temperature from clumped isotopes of these same carbonates. These results can be used to evaluate and refine proposed mechanisms of formation of the high central Rockies and help determine whether the Rocky Mountains have recently gained elevation or are a long-dead mountain chain. Broader impacts of this study include providing early career support for a female assistant professor. The study also establishes an innovative methodology by integrating three sets of stable isotope data with basin sedimentology to provide a means of distinguishing climate change from surface uplift. In addition, this study integrates with other similar, NSF-supported, research initiatives that cover other areas of the western U.S. to paint a broader picture of recent vertical movements of the land surface across the region. Lastly results of this study are to be incorporated into an electronic presentation that will form part of an installation at the Geology Museum on the University of Wyoming campus. The museum is a frequent destination for middle and high school classes from across the state, as well as a stop for other visitors. This presentation will provide insight into the origins of high elevation across the state and region.