Regional piedmont incision during base-level rise in the northeastern Sonoran Desert, Arizona, USA
Regional piedmont incision during base-level rise in the northeastern Sonoran Desert, Arizona, USA
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DOI：
10.1080/02723646.2021.1934964
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发表时间：
2021-07
影响因子：
1.6
通讯作者：
Christian González;M. Kelley;M. Marvin;Norma López-Castañeda;R. Dorn;M. Schmeeckle
中科院分区：
文献类型：
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作者：
Christian González;M. Kelley;M. Marvin;Norma López-Castañeda;R. Dorn;M. Schmeeckle
摘要美国索诺兰沙漠东北部的山前(包括冲积扇和山脚)上切割着短暂的河道。位于大都市凤凰城周围，这一构造平静的地区在整个上新世只经历了内陆型构造盆地的沉积。然后，在更新世开始时，盐河和吉拉河合并，随后出现了一波沉积。在第四纪的其余部分，皮埃蒙特基准面的增加仍在继续。本文探讨了两种假设来解释山前切割，尽管基准面在上升。经典的解释是，随着沙漠山脉规模的缩小，切割是其演化的一部分。我们在这里提出的一种新的替代方案涉及到基准面的横向转移，从上新世的内陆型盆地沉积到距离山脉前缘更近的位置，以响应河流整合。我们提出了一种将山墙纵向轮廓建模为一维扩散系统的思维练习，并分析了埃斯特雷拉山脉冲积扇的切割。虽然我们对山脚的一维建模结果与对山脉前缘切口的两种解释都一致，但埃斯特雷拉·巴贾达山脉的切口最好的解释是基准面突然移动到沙漠山麓的脚趾。
ABSTRACT Ephemeral channels incise into the piedmonts (both alluvial fans and pediments) of the northeastern Sonoran Desert, USA. Located around metropolitan Phoenix, this tectonically quiescent region experienced only aggradation in endorheic structural basins throughout the Pliocene. A wave of aggradation then followed Salt and Gila river integration at the start of the Pleistocene. Aggradation of piedmont base levels continued throughout the rest of the Quaternary. This paper explores two hypotheses to explain piedmont incision despite rising base levels. The classic explanation is that incision is part of the evolution of desert mountain ranges as they decrease in size. A new alternative we propose here involves a lateral shift in base level from Pliocene endorheic basin playas to positions kilometers closer to range fronts in response to river integration. We present a thought exercise of modeling a pediment longitudinal profile as a 1D diffusive system, and we also analyze incision into alluvial fans of the Sierra Estrella range. While our 1D modeling results for pediments are consistent with both explanations for range-front incision, Sierra Estrella bajada incision is best explained by the sudden relocation of the base level to the toe of desert piedmonts.