Global Change: Genesis & Paleoenvironmental Record of Dunes on the Southern High Plains

本研究旨在探讨南部高平原沙丘场和沙丘滩的古气候意义和晚第四纪历史。本文将检验三个主要假设：1)南方高原区的沙丘田在公元前9000年至4500年之间、公元前1000年以来和历史上同步形成；2)晚第四纪南部高原区的月形岩是同期和幕式形成的，它们是在干旱时期由邻近的playas沉积形成的；3)全新世沙丘和新月形沙丘的形成是同步发生的，是区域干旱的结果。这项研究有几个重要的方面。沙丘构造和沙丘运动的记录应提供高平原地表干旱和风蚀的长期（晚第四纪）记录。研究沙丘活动的历史记录和历史气候数据将开始提供一些在该地区沙漠化开始之前必须跨越的气候阈值的估计。研究月牙岩也很重要，因为它们是Llano Estacado上唯一一个具有可追溯到过去3万多年的古环境和地层记录潜力的沉积地点。对南部高平原的拟议研究补充了目前对北部高平原的沙丘研究（由美国国家科学基金会、美国地质调查局和美国国家航空航天局资助），并将有助于对晚第四纪风成时期侵蚀和沉积及其伴随的气候影响的次大陆尺度的看法。

The proposed research is an investigation of the paleoclimatic significance and late-Quaternary history of sand dune fields and lunettes (dunes fringing playa basins) on the Southern High Plains. Three principal hypotheses will be tested: 1) the sand dune fields on the Southern High Plains formed synchronously between 9000 and 4500 yrs B.P., since 1000 yrs B.P., and historically; 2) the lunettes of the Southern High Plains formed synchronously and episodically during the late Quaternary and were derived from sediments in adjacent playas during droughts; 3) Holocene construction of the sand dunes and the lunettes occurred synchronously and was the result of regional drought. There are several significant aspects of the research. The record of dune construction and dune movement should provide a long-term (late Quaternary) record of drought and wind erosion of the High Plains surface. Studying the historic record of dune activity along with historic climate data will begin to provide some estimates of the climatic thresholds that must be crossed before desertification begins in the region. Studying the lunettes is also important because they are the only sites of deposition on the Llano Estacado with a demonstrated potential for a dateable paleoenvironmental and stratigraphic record spanning the past 30,000+ years. The proposed research on the Southern High Plains complements current dune studies on the Northern High Plains (sponsored by NSF, USGS, and NASA) and will contribute to a subcontinental-scale view of late-Quaternary eolian erosion and sedimentation and attendant climatic implications.