Climate projections for the North American Southwest (NASW) predict an increasing frequency and duration of droughts over the 21st century in response to human-induced warming, with potentially severe economic and social consequences. The geological record provides a way to contextualise this prediction because of the past occurrence of abrupt hemispheric warming events and sustained intervals of atmospheric carbon dioxide loading equivalent to those projected for AD 2100 (between ∼500 and 900 ppmv). Yet, terrestrial climate archives are typically too short and incomplete to provide a full record of these events. In principle, drill cores from deep sea sediments in the eastern Pacific Ocean can be used to overcome this problem because they contain long records of continental dust and distal riverine-supplied sediments from North America. Yet our limited understanding of the provenance and transport pathways of these sediments impedes use of these marine archives for this purpose. Here we present radiogenic isotope data (Sr, Nd and Pb) from known NASW dust-producing hot spots – playa lakes in the Mojave Desert, Quaternary silts mantling the California Channel Islands and the terrigenous fraction from marine sediments of the eastern Pacific Ocean, supported by new maps of bedrock isotopic composition in the NASW. We use these and published data sets to infer the origin of playa lake silts in the Mojave Desert and the source of windblown sediments to the California Channel Islands and nearby ocean basins. Our Results rule out a significant contribution from the distal tails of either the Pacific Asian dust plume or the North African dust plume to the Quaternary Channel Island silt mantles, corroborating the suggestion that they are aeolian in origin and sourced from the NASW on the Santa Ana winds. We identify the Outer California Borderland basins as an attractive proposition for studying past dust flux and palaeoaridity in the North American Southwest.

北美西南部（NASW）的气候预测预测，在21世纪，由于人类引起的变暖，干旱的频率和持续时间将增加，并可能带来严重的经济和社会后果。地质记录为这种预测提供了一种方法，因为过去发生了突然的半球变暖事件，并且大气二氧化碳负荷的持续时间间隔与公元2100年的预测时间相当（在500至900 ppmv之间）。然而，陆地气候档案通常太短且不完整，无法提供这些事件的完整记录。原则上，东太平洋深海沉积物的岩心可以用来解决这个问题，因为它们记录了北美大陆的长期粉尘和河流向上游提供的沉积物的悠久记录。然而，我们对这些沉积物的来源和运输途径的有限了解阻碍了为此目的使用这些海洋档案。在这里，我们提供了来自已知NASW产生尘埃的热点的放射性同位素数据（Sr，Nd和Pb）-莫哈韦沙漠的普拉亚湖，加利福尼亚海峡群岛的第四纪粉砂和东太平洋海洋沉积物中的陆源部分，得到了支持通过NASW的新基岩同位素组成图。我们使用这些数据和已发布的数据集来推断莫哈韦沙漠中普拉亚湖淤泥的起源以及加利福尼亚海峡群岛和附近海盆的风吹沉积物来源。我们的结果排除了亚太粉尘羽流或北非粉尘羽流的末尾对第四纪海峡岛淤泥地幔的重大贡献，从而证实了它们起源于风沙，并来自圣安娜的NASW的暗示。风。我们认为外加州边境地区盆地是研究北美西南地区过去尘埃通量和古干旱的诱人提议。