Separating Regional and Local Components of Uplift in the Western Transverse Ranges of California to Test Models of Mountain Belt Formation

分离加利福尼亚州西部横向山脉的区域和局部隆起部分以测试山带形成模型

• 批准号: 1839301
• 负责人: Nathan Onderdonk
• 金额: $ 21.66万
• 依托单位: California State University-Long Beach Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1839301&HistoricalAwards=false
• 关键词: Separating; Regional; Local; Components; Uplift

The origin and development of mountain belts has long been of special interest to people and a primary target of research in the Earth Sciences. This study will advance our scientific understanding of the processes that control the uplift of mountains by studying the patterns and rates of elevation change in an actively-growing mountain belt. The western Transverse Ranges of California are being uplifted by compression along the boundary between the North American and Pacific tectonic plates. In addition to the uplift of individual mountain ranges along specific faults, the lower valley areas are also rising, indicating a deeper cause to the regional uplift of the mountains. Old floodplains that have been lifted above their rivers by tectonic forces will be used as reference markers to measure the amount and rate of tectonic uplift and investigate how local vs. regional mechanisms contribute to mountain growth. The scientific advances associated with this project are coupled with training and education of both graduate and undergraduate students at a Hispanic Serving Institution that emphasizes inclusion of underrepresented groups in Science, Technology, Engineering, and Mathematics (STEM) fields. The project will also benefit the local population of southern California through enhancing understanding of regional seismic hazards posed by the faults that bound and underlie the western Transverse Ranges. Regional uplift affects an entire mountain belt, whereas local uplift results in the production of relief in the form of individual ranges and valleys. The western Transverse Ranges (WTR) of California are an active fold and thrust belt where high rates of shortening have been interpreted from geodetic studies and from geologic reconstructions. Uplift rates based on marine terraces and river terraces along the southern coast of the WTR are as high as 7 millimeters per year but vary dramatically along the coast across faults and folds that trend oblique to the coast. These high uplift rates, as measured in the elevated hanging walls of reverse faults or actively growing anticlines, are local uplift rates that are most likely not characteristic of the entire mountain belt. This project will develop a more complete picture of topographic development in the WTR by using previously unstudied fluvial strath terraces present within the WTR, and marine terraces along the western coast, as markers for vertical deformation across the mountain belt. The terraces have been offset and lifted in the hangingwalls of reverse faults, but their presence in the footwall valleys as well indicate an additional component of regional uplift that must be occurring on deeper structures. Thus, it is possible to measure both local and regional uplift and separate the two components. Luminescence and radiocarbon dating will be used to establish a Late Quaternary chronology of the terraces to calculate the timing and rate of deformation and topographic development.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.

山地带的形成和发展一直是人们特别感兴趣的问题，也是地球科学研究的主要对象。这项研究将通过研究一个活跃生长的山区地带的海拔变化的模式和速率，推进我们对控制山脉隆起的过程的科学理解。加州的西部横贯山脉正被沿着北美和太平洋构造板块之间的边界的挤压抬升。除了个别山脉沿着特定断层隆升外，低谷地区也在隆升，这表明山脉区域隆升有更深层次的原因。被构造力抬升到河流上方的旧洪泛区将被用作参考标记，以测量构造抬升的数量和速率，并研究当地与区域机制如何促进山脉生长。与该项目相关的科学进步与西班牙裔服务机构的研究生和本科生的培训和教育相结合，该机构强调在科学，技术，工程和数学（STEM）领域纳入代表性不足的群体。该项目还将使南加州的当地居民受益，因为他们将进一步了解西部横贯山脉边界和下面的断层所造成的区域地震危险。区域性隆起影响整个山脉带，而局部隆起则导致以个别山脉和山谷形式出现的地貌。加州的西横岭（WTR）是一个活跃的褶皱和冲断带，在那里的高缩短率已被解释为大地测量研究和地质重建。基于WTR南部海岸沿着的海洋阶地和河流阶地的Ucrossing率高达每年7毫米，但沿海岸沿着的断层和褶皱（倾向于倾斜于海岸）变化很大。在逆断层或活跃生长的背斜的隆起上盘中测量到的这些高隆起速率是局部隆起速率，很可能不是整个山脉带的特征。本项目将通过使用WTR内先前未研究的河流斯特拉特阶地和沿西海岸沿着的海洋阶地，作为山脉带垂直变形的标志，绘制WTR地形发展的更完整图像。逆断层上盘的阶地已被抵消和抬升，但它们在下盘山谷中的存在也表明了区域隆升的另一个组成部分，必须发生在更深的构造上。因此，可以测量局部和区域隆起并将两个分量分开。发光和放射性碳测年将用于建立阶地的晚第四纪年代学，以计算变形和地形发展的时间和速率。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。