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.

Abstractthis项目旨在研究中央盆地一部分的地形演变，以及在最近的新生代扩展构造时期。多种古升高，地质研究和地球物理模型交替地预测，西部已经经历了明显的晚期新生代升高或大量大量的恢复后期的新生代，或至少与大范围内的内在构造构成。这些不同的结果部分可能是由于西部西部的地质复杂性，并且许多研究领域可能在周末发生了构造历史。拉斯维加斯和内华达山脉之间的中央盆地和山脉省是研究美国西部古代图演变的理想地点，因为1）已完成的广泛传播和详细的地质映射，导致了相当完整的第三级延伸的壁画重建； 2）在描述地壳结构的区域中，最近的被动和主动地震和其他地球物理实验和3）研究研究了使用异种石和火山岩地球化学的同一时期，研究了子碱和岩石圈的演化。一个新开发的基于玄武岩流囊泡的古升温表非常适合解决此问题，因为该研究区域中玄武岩的广泛覆盖，流量的广泛年龄范围以及使它们相对新鲜的沙漠环境。 PI提议在从内华达山脉到春天的内华达州的300公里样带中对大约40个地点进行古占地，并确定从中新世晚期到上新世或近期这些地点的古含量。这项研究具有广泛的影响。首先，它强烈依靠这样的假设，即在美国和全球范围内，晚期新生代的癫痫症影响了气候。这项工作还将多年在开发地图查看盆地的壁式重建和范围扩展方面的工作联系在一起，并通过在变形中增加第三维，最后，这项研究将是使用新开发的高度计的第一项广泛的构造研究。与高空计的开发人员和处理样品的分析设施的合作都应导致简化的过程，以使该高度计的未来使用，以及测试并证明其在构造研究中的使用。