ABSTRACT

A high-resolution record of fluvial, aeolian and lacustrine deposits of Late Pleistocene age is exposed along the Neales Cliff in the lower reaches of the Nappamurra-Neales River, western Kati Thanda-Lake Eyre (KT-LE). Five major stratigraphic units reflect a variety of changes in sedimentary processes, depositional environments and hence palaeo-lake level fluctuations. This detailed record of a dryland terrestrial sedimentary succession in the northern part of KT-LE enables comparison to contemporaneous sequences in the southern part of KT-LE. The sedimentary record from the Neales Cliff area is placed into a continental stratigraphic framework, in which changes in sediment accumulation and depositional style are linked to climatically driven palaeo-lake level fluctuations independent of eustatic sea-level changes. Following the ~200 ka interglacial maximum, a drying-up systems tract is represented by a fluvial fining-upward trend, capped by palaeosols. A wettening-up systems tract followed, when lake level rose to +10 m AHD during the last interglacial, resulting in a lacustrine succession but punctuated by regular desiccation events. During the following drying-up systems tract, progressive lake-level fall resulted in deep incision around 100 ka, followed by enhanced fluvial deposition of fine-grained sediments. A brief rise in base level resulted in a wettening-up systems tract comprising a thin veneer of fluvial/alluvial sediments followed by extensive dune build-up and desert pavement development during the Last Glacial Maximum. Subsequent lake level fall to the present lake level of −15 m AHD, resulted in deep incision of up to 10 m by the modern day Nappamurra-Neales River.

摘要

沿 Nappamurra-Neales 河下游、Kati Thanda-Lake Eyre (KT-LE) 下游的 Neales Cliff 揭示了晚更新世河流、风成和湖相沉积物的高分辨率记录。五个主要地层单元反映了沉积过程、沉积环境和古湖水位波动的各种变化。KT-LE 北部旱地陆相沉积序列的详细记录可以与 KT-LE 南部的同期序列进行比较。Neales Cliff 地区的沉积记录被置于大陆地层框架中，其中沉积物积累和沉积方式的变化与气候驱动的古湖水位波动有关，与海平面变化无关。在~200 ka间冰期最大值之后，干涸的系统域以河流细化向上趋势为代表，以古土壤为上限。随后是润湿系统区域，在最后一次间冰期湖水位上升至 +10 m AHD 时，导致湖泊连续，但不时出现定期的干燥事件。在随后的干涸系统域中，湖面逐渐下降导致约 100 ka 的深度切口，随后细粒沉积物的河流沉积增强。基础水平的短暂上升导致了一个湿润系统区域，包括一层薄薄的河流/冲积沉积物，随后在末次盛冰期期间广泛的沙丘堆积和沙漠路面的发展。随后的湖水位下降到现在的-15 m AHD湖水位，