The widespread formation of organic rich sediments in south-east Australia during the Holocene (Marine Isotope Stage [MIS] 1) reflects the return of wetter and warmer climates following the Last Glacial Maximum (LGM). Yet, little is known about whether a similar event occurred in the region during the previous interglacial (MIS 5e). A 6.8 m sediment core (#LC2) from the now ephemeral Lake Couridjah, Greater Blue Mountains World Heritage Area, Australia, provides insight into this question. Organic rich sediments associated with both MIS 1 and 5e are identified using ¹⁴C and optically stimulated luminescence (OSL) dating techniques. Also apparent are less organic sedimentary units representing MIS 6, 5d and 2 and a large depositional hiatus. Sediment δ¹³C values (−34 to −26‰) suggests that C₃ vegetation dominates the organic matter source through the entire sequence. The pollen record highlights the prevalence of sclerophyll trees and shrubs, with local hydrological changes driving variations in the abundance of aquatic and lake-margin species. The upper Holocene sediment (0–1.7 m) is rich in organic matter, including high concentrations of total organic carbon (TOC; 20–40%), fine charcoal and macrophyte remains. These sediments are also characterised by a large proportion of epiphytic diatoms and a substantial biogenic component (chironomids and midges). These attributes, combined with low δ¹³C and δ¹⁵N values, and C:N ratios of approximately 20, indicate a stable peat system in a swamp like setting, under the modern/Holocene climate. In comparison, the lower organic rich unit (MIS 5e-d) has less TOC (5–10%), is relatively higher in δ¹³C and δ¹⁵N, and is devoid of macrophyte remains and biogenic material. Characterisation of the organic matter pool using ¹³C-NMR spectroscopy identified a strong decomposition signal in the MIS 5e organic sediments relative to MIS 1. Thus the observed shifts in δ¹³C, δ¹⁵N and C:N data between the two periods reflects changes in the organic matter pool, driven by decompositional processes, rather than environmental conditions. Despite this, high proportions of aquatic pollen taxa and planktonic diatoms in the MIS 5e–d deposits, and their absence in the Holocene indicates that last interglacial Lake Couridjah was deeper and, or, had more permanent water, than the current one.

在全新世（海洋同位素阶段[MIS] 1）期间，澳大利亚东南部广泛形成的富含有机物的沉积物反映了上一次冰期最高峰（LGM）之后湿润和温暖的气候的回归。然而，人们对先前的冰间期（MIS 5e）期间该地区是否发生过类似事件知之甚少。来自澳大利亚大蓝山世界遗产地的现在短暂的库里贾湖（Lake Couridjah）的6.8 m沉积物岩心（＃LC2）提供了对该问题的见解。使用¹⁴ C和光学激发发光（OSL）测年技术可以识别与MIS 1和5e相关的富含有机物的沉积物。同样明显的是，代表MIS 6、5d和2的有机沉积单元较少，沉积裂隙较大。沉积物δ ¹³C值（-34至-26‰）表明，C ₃植被在整个序列中主导着有机物源。花粉记录突出显示了硬叶树和灌木的流行，局部水文变化驱动了水生和湖缘物种丰富度的变化。全新世上层沉积物（0-1.70 m）富含有机物，包括高浓度的总有机碳（TOC； 20-40％），细木炭和大型植物。这些沉积物的特征还在于大部分附生硅藻和大量生物成因（手足类和mid类）。这些属性，具有低δ组合¹³ C和δ ¹⁵N值和C：N比率约为20，表明在现代/全新世气候下，沼泽环境中的泥炭系统稳定。相比较而言，下面的有机丰富单元（MIS 5E-d）具有以下TOC（5-10％），在δ相对较高的¹³ C和δ ¹⁵ N，并且没有水生植物遗迹和生物材料构成。使用有机物质池的表征¹³ C-NMR光谱确定了MIS 5E有机沉积物相对于MIS 1.强烈分解信号。因此在δ所观察到的位移¹³ C，δ ¹⁵两个时期之间的N和C：N数据反映了有机物质池的变化，这是由分解过程而非环境条件驱动的。尽管如此，MIS 5e-d矿床中水生花粉类群和浮游硅藻的比例很高，而它们在全新世中的缺失表明，最后一个冰间湖库里贾湖比目前的湖深，或者拥有更多的永久水。