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.

在沙漠环境中冲积扇的形成仍然是一个有争议的主题，在特定地区的风扇形成的概念模型的应用程序与不同的气候背景的地区一般缺乏强大的定量支持。 这一国际合作项目旨在通过测试墨西哥下加利福尼亚半岛南部晚第四纪冲积扇形成的替代假设，将数据输入这些概念模型。 中心假设是，热带气旋在此期间进行了大部分的地貌工作，季节性高强度降水已耦合到基岩的快速风化，以产生循环冲积扇加积响应千年尺度的气候变化。 将通过详细分析晚更新世-全新世沉积单元的沉积学和土壤发育情况来支持宇宙成因核素深度剖面年龄测定和光释光深度剖面测年。 这些技术的目的是同时确定山坡上的沉积物产生量和冲积单元中的输送和积累速率。 研究结果将清楚显示冲积单位何时建成、冲积表面何时稳定、沉积物沉积的速度，以及沉积物在运输和沉积之前在山坡上储存了多久。 该项目（由NSF的地貌学和土地利用动态学、P2 C2和EPSCoR项目以及国际科学与工程办公室支持）将产生更多科学受众和更广泛公众感兴趣的数据集和知识。 首先，我们将测试北美西南部沙漠冲积扇加积的广泛使用的模型。 其次，我们将测试热带气旋的相关性如何在这一地区千年的时间尺度上演变，并帮助分析热带气旋对世界其他干旱和半干旱地区的影响。（特别是，我们将与评估过去几个世纪东太平洋热带气旋活动及其对美国西南部快速增长地区生态系统和人口影响的研究联系起来，墨西哥西北部，以改善这些风暴的危险特性）。 第三，我们更精确的冲积扇表面通常用作古地震学标志的相关性将改善地震复发间隔和本地和区域断层滑动率的确定，不仅在下加利福尼亚的邻近地区，而且在所有干旱的北美西南部和其他地区，冲积面被用来推断地震复发率，增加我们的断层运动学的理解。