Quaternary Geochronology: Eastern Sahara and American West

此前由美国国家科学基金会资助的对极度干旱的撒哈拉东部的研究已经建立了一个跨越第四纪的不连续的地质年代序列。埋藏“雷达谷”的早至中更新世冲积物和风成沉积物与中旧石器时代考古相关，被与中旧石器时代考古相关的湖泊沉积物所嵌入。它们被全新世的沙层、盐湖沉积物和层叠湖床覆盖，并伴有新石器时代的考古发现。基于地质、考古、动物群和孢粉学的古气候和古环境解释表明，晚第四纪萨赫勒-撒哈拉过渡带发生了主要的南北波动。Meidob山是一个玄武岩火山堆，在过去的3000万年里，它周期性地活跃，位于撒哈拉沙漠的南部边缘，因此，它经历了数次过渡带的来回穿越。在一个跨学科团队的合作下，我建议研究冲积和风成沉积物与可测定的火山相互作用，以建立一个时间校准的地层序列，该序列将与撒哈拉沙漠极度干旱的核心地层以及向南到非洲裂谷序列相关联。研究结果将有助于理解敏感的撒哈拉边缘地区过去的人地关系，以便更好地评估未来的土地利用，并将极度干旱的地貌过程与半干旱的美国西部进行比较。调查技术包括地层学、沉积学、孢粉学、AMS放射性碳测年、空间图像遥感、同位素地球化学和考古观测。早期人类遗骸的可能性不会被忽视。

Previous NSF-sponsored research in the hyperarid eastern Sahara has established a discontinuous geochronological sequence spanning the Quaternary. Early to Middle Pleistocene alluvium and eolian sediments with Early Paleolithic archaeology in buried "radar" valleys are inset by lacustrine deposits associated with Middle Paleolithic archaeology. These are overlain by Holocene sand sheets, playa deposits, and laminated lake beds with associated Neolithic archaeology. Paleoclimatic and paleo- environmental interpretations based upon geology, archaeology, fauna, and palynology indicate major north-south fluctuations of the Sahelio-Saharan transitions zone during late Quaternary time. The Meidob Hills, a basaltic volcanic pile, periodically active for perhaps the past 30 millions years, lies on the present southern fringe of the Sahara and has, therefore, experienced the passage of the transition zone back and forth several times. With the collaboration of an interdisciplinary team I propose to study alluvial and eolian sediments interbeded with datable volcanics to establish a time-calibrated strati- graphic sequence that will be correlatable to strata of the hyperarid core of the Sahara as well as southward to African rift valley sequences. The results will be of value in understanding past man-land relationships in the sensitive Saharan fringe in order to better assess future land uses and also in comparing hyperarid geomorphic processes with semiarid American West. Investigative techniques include stratigraphy, sedimentology, palynology, AMS radiocarbon dating, space imagery remote sensing, isotope geochemistry, and archaeological observations. The possibility for early hominid remains will not be overlooked.