Abstract The dynamics of river systems are most easily studied by observing their present geomorphology exposed at Earth's surface. However, the bulk of these often long-lived transportation and depositional systems is mostly buried at depth and hidden from view. Accessing these subsurface archives is often not possible. The Phoenix ‘basin’ of Arizona, USA, with its rich collection of water well drilling information, offers a unique opportunity. Clast assemblages of sand and gravel deposits contained in subsurface drill cuttings enable estimates of sediment provenance and, importantly, reveal changes of provenance over time. This study represents more than a decade of drill cuttings analysis and presents a method for evaluating the depositional history of how the Phoenix basin developed a large external river system that crossed a long-lived internally drained basin. This configuration developed after Basin and Range faulting and extension had ceased, allowing the basin to fill to capacity with sediment. When placed in the context of a series of new isopach maps of the subsurface ancestral Salt River deposits, our clast assemblage analysis supports the conclusion that the Salt and Verde rivers appeared suddenly in the geologic record. The ancestral Salt River deposits and other nearby streams crossing the basin each possess a unique clast assemblage that can be used to ‘fingerprint’ sediments with similar sources. We use these observations to draw conclusions about the age and origin of these streams. Used in conjunction with other types of analyses such as cosmogenic burial dating and detrital zircon analyses, determining clast assemblages of drill cuttings in the context of mapping these assemblages is a powerful new method for estimating the source of sediment and for understanding how the Phoenix basin, and basins in general, fill with sediment. This information is of value in modeling both basin development and groundwater resources in similar contexts in Arizona and elsewhere.

中文翻译：

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盐河突然汇入美国亚利桑那州内部排水盆地和山脉省的地下证据

摘要 河流系统的动力学最容易通过观察它们目前暴露在地球表面的地貌来研究。然而，这些通常寿命很长的运输和沉积系统中的大部分大部分都被埋在深处并且看不见。访问这些地下档案通常是不可能的。美国亚利桑那州凤凰城的“盆地”拥有丰富的水井钻井信息，提供了一个独特的机会。地下钻屑中包含的沙子和砾石沉积物的碎屑组合能够估计沉积物来源，重要的是，可以揭示来源随时间的变化。这项研究代表了十多年的钻屑分析，并提出了一种方法来评估凤凰盆地如何发展穿过一个长期存在的内部排水盆地的大型外部河流系统的沉积历史。这种构造在盆地和山脉断层和伸展停止后发展起来，使盆地充满沉积物。当置于一系列地下祖先盐河沉积物的新等厚图的背景下时，我们的碎屑组合分析支持盐河和佛得河在地质记录中突然出现的结论。祖先的盐河沉积物和其他附近穿过盆地的河流都拥有独特的碎屑组合，可用于“指纹”具有相似来源的沉积物。我们使用这些观察得出关于这些流的年龄和起源的结论。与其他类型的分析（例如宇宙成因埋藏年代和碎屑锆石分析）结合使用，在绘制这些组合的背景下确定钻屑的碎屑组合是一种强大的新方法，可用于估算沉积物来源并了解凤凰盆地如何，和盆地一般，充满沉积物。这些信息对于模拟亚利桑那州和其他地方类似背景下的流域开发和地下水资源很有价值。在绘制这些组合物的地图的背景下确定钻屑的碎屑组合是估计沉积物来源和了解凤凰盆地和一般盆地如何充满沉积物的一种强有力的新方法。这些信息对于模拟亚利桑那州和其他地方类似背景下的流域开发和地下水资源很有价值。在绘制这些组合物的地图的背景下确定钻屑的碎屑组合是估计沉积物来源和了解凤凰盆地和一般盆地如何充满沉积物的一种强有力的新方法。这些信息对于模拟亚利桑那州和其他地方类似背景下的流域开发和地下水资源很有价值。