Collaborative Research: Tropical cyclone imprint on late Quaternary alluvial fans of Baja California: Key for understanding arid regions landscape evolution

合作研究：热带气旋对下加利福尼亚州晚第四纪冲积扇的印记：理解干旱地区景观演化的关键

• 批准号: 1123481
• 负责人: Jose Luis Antinao Rojas
• 金额: $ 26.65万
• 依托单位: Nevada System of Higher Education, Desert Research Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1123481&HistoricalAwards=false
• 关键词: Collaborative; Research; Tropical; cyclone; imprint

Alluvial fan formation in desert environments is still a debated subject, and application of conceptual models developed for fan formation in specific regions to areas with different climate settings generally lacks robust quantitative support. This international collaborative project aims to input data into these conceptual models by testing alternate hypotheses on the formation of Late Quaternary alluvial fans in the southern Baja California peninsula in Mexico. The central hypothesis is that tropical cyclones have performed most of the geomorphic work during this period and that seasonal high intensity precipitation has been coupled to rapid weathering of bedrock to generate cyclic alluvial fan aggradation in response to millennial-scale climate variability. Combined cosmogenic nuclide depth profile age determination and optically stimulated luminescence depth profile dating will be supported with detailed analyses of sedimentology and soil development of the sedimentary units in the Late Pleistocene-Holocene. These techniques are aimed to determine simultaneously sediment production on the hillslopes and delivery and accumulation rates in the alluvial units. The results will yield a clear picture of when the alluvial units were built, when the alluvial surfaces stabilized, how fast sediment was deposited, and how long the sediment was stored in the hillslopes before transport and deposition. This project (supported by NSF's programs in Geomorphology and Land Use Dynamics, P2C2, and EPSCoR, and Office of International Science and Engineering) will produce datasets and knowledge that are of interest to a larger scientific audience and to the broader public. First, we will test a widely used model of alluvial fan aggradation for the deserts of southwestern North America. Second, we will test how the relevance of tropical cyclones has evolved over millennial timescales in this area and help to analyze tropical cyclone effects in other arid and semi-arid regions of the world (in particular, we will link with studies that assess activity of Eastern Pacific tropical cyclones over the last centuries and their effects on ecosystems and human population in the rapidly growing areas of southwestern U.S. and northwestern Mexico to improve hazard characterization of these storms). Third, our more precise correlation of alluvial fans surfaces normally used as paleoseismological markers will improve determination of earthquake recurrence intervals and of local and regional fault slip rates, increasing our understanding of fault kinematics not only in neighboring areas in Baja California but also in all arid southwestern North America and other regions where alluvial surfaces are used to infer earthquake recurrence rates.

沙漠环境中的冲积粉丝形成仍然是一个有争议的主题，并且在特定地区为不同气候环境的地区开发了为粉丝形成而开发的概念模型通常缺乏强大的定量支持。 该国际协作项目的目的是通过测试墨西哥南部巴哈加州半岛的季四月冲积球迷形成的替代假设，将数据输入这些概念模型。 中心假设是，在此期间，热带气旋进行了大多数的地貌工作，并且季节性高强度降水已与基岩的快速风化耦合，以响应千年的气候变异性，从而产生环状冲积风扇促进。 宇宙基因核素深度分布年龄的确定和光学刺激的发光幅度谱谱将通过详细的沉积学和土壤发育的详细分析来支持晚期更新世后代晚期沉积单元的发育。 这些技术的目的是确定在山坡上同时产生沉积物，以及冲积单元的交付和积累率。 结果将清楚地了解何时建造冲积单元，冲积表面稳定，沉积物的沉积速度以及在运输和沉积之前将沉积物存储在山坡中的时间。 该项目（由NSF的地貌学和土地使用动态计划，P2C2和EPSCOR以及国际科学与工程办公室的支持）将产生对更大的科学受众和更广泛的公众感兴趣的数据集和知识。 首先，我们将对北美西南部沙漠的冲积粉丝融化模型进行广泛使用的模型。 其次，我们将测试热带气旋的相关性如何在该领域的千禧年时间尺度上发展，并有助于分析世界其他干旱和半干旱地区的热带气旋影响（尤其是我们将与评估东部太平洋飓风的活动相关联（我们将与上一个百分国家及其对米尔斯人的近代人的影响越来越快，远来如此远的人类人类的影响改善这些风暴的危害表征）。 第三，我们对冲积风扇表面的更精确的相关性通常用作古植物学标志物，将改善地震复发间隔和当地和区域断层滑移速率的确定，从而增强我们对在加利福尼亚州巴哈邻近地区的缺陷运动学的理解，不仅在加利福尼亚州的邻近地区，而且在所有北部北美地区和其他区域均与其他区域相关的地方，都将在各个区域内相处。