Paleotopography of an Evolving Extensional Orogen, the Central Basin and Range, Western United States

美国西部中央盆地和山脉演化中的伸展造山带的古地貌

• 批准号: 0310252
• 负责人: Nathan Niemi
• 金额: $ 12.65万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-10-01 至 2006-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0310252&HistoricalAwards=false
• 关键词: Paleotopography; Evolving; Extensional; Orogen; Central

AbstractThis project is designed to look at the topographic evolution of a portion of the central Basin and Range in the western United States during a period of late Cenozoic extensional tectonism. A variety of paleoaltimeters, geologic studies, and geophysical models have alternately predicted that the western United States has experienced either significant late Cenozoic uplift or substantial late Cenozoic lowering due to, or at least synchronous with, large magnitude intracontinental tectonism. In part these disparate results may be due to the geologic complexity of the western United States, and the fact that many of the study areas may have undergone differing tectonic histories in late Cenozoic time. The central Basin and Range province, between Las Vegas and the Sierra Nevada is an ideal locality to study the paleotopographic evolution of the western United States because of 1) the wide spread and detailed geologic mapping that has been completed, resulting in a fairly complete palinspastic reconstruction of Tertiary extension; 2) recent passive and active seismic and other geophysical experiments in the region which delineate the crustal structure and 3) studies that have examined the evolution of the sub-Basin and Range lithosphere through this same time period using xenoliths and the geochemistry of volcanic rocks. A newly developed paleoaltimeter based on basalt flow vesicles is well suited for approaching this problem due to the extensive coverage of basalts in this study area, the broad age range of the flows, and the desert environment which keeps them relatively fresh. The PI proposes to sample approximately 40 sites for paleoaltimetry across a 300 km transect from the Sierra Nevada to the Spring Mountains, Nevada and determine the paleoelevations of these sites from late Miocene to Pliocene or Recent time.This study has broad impacts for several reasons; first it bears strongly on the hypothesis that late Cenozoic epierogeny has affected climate, both in the United States and globally. The work also ties together years of work in developing map view palinspastic reconstructions of Basin and Range extension by adding a third dimension to the deformation, and finally, this study will be the first broad tectonic study using the newly developed altimeter. Collaborations with both the developers of the altimeter and the analytical facilities which process the samples should result in a streamlined process for future use of this altimeter, as well as testing and demonstrating its use in tectonic studies.

摘要该项目旨在研究晚新生代伸展构造运动期间美国西部中部盆地和山脉部分地区的地形演化。各种古高度计、地质研究和地球物理模型交替预测，由于大规模的陆内构造运动或至少与之同步，美国西部经历了晚新生代显着的抬升或晚新生代的大幅下降。这些不同的结果在一定程度上可能是由于美国西部的地质复杂性，以及许多研究区域在新生代晚期可能经历了不同的构造历史这一事实。位于拉斯维加斯和内华达山脉之间的中部盆地和山脉省是研究美国西部古地形演化的理想地点，因为：1）已经完成了广泛而详细的地质测绘，形成了相当完整的古地形图第三系延伸的重建； 2) 最近在该地区进行的被动和主动地震和其他地球物理实验，描绘了地壳结构；3) 使用捕虏体和火山岩地球化学研究了同一时期次盆地和山脉岩石圈的演化。新开发的基于玄武岩流囊泡的古高度计非常适合解决这个问题，因为该研究区域玄武岩覆盖面广，玄武岩流的年龄范围广，而且沙漠环境使其保持相对新鲜。 PI 提议对从内华达山脉到内华达州斯普林山 300 公里横断面的大约 40 个地点进行古海拔测量，并确定这些地点从中新世晚期到上新世或近代的古海拔。这项研究具有广泛的影响，原因如下：首先，它强烈支持新生代晚期表生作用影响美国和全球气候的假设。这项工作还通过在变形中添加第三个维度，将多年来开发盆地和山脉延伸的地图视图回弹重建的工作联系起来，最后，这项研究将是第一个使用新开发的高度计进行广泛的构造研究。与高度计开发商和处理样本的分析设施的合作应该会简化该高度计未来使用的流程，并测试和展示其在构造研究中的用途。