The River Murray Estuary, South Australia exhibits a morphology typical of a wave-dominated estuary and comprises two large, shallow central basin lakes – Lakes Alexandrina and Albert. Contested interpretations of the estuary’s limnological history and uncertainty surrounding the sustainability of current basin water usage practice warrant a robust investigation into how the system has evolved. Here we combine lithostratigraphic, geochemical and sedimentological evidence from a transect of sediment cores to reconstruct the sediment infill history of the system. We uncover multiple stages of sediment infill over the history of the system, associated with (1) the low gradient morphology of the estuary and lower river channel, (2) the mid- to late-Holocene sea-level regression and (3) anthropogenic modifications to the fluvio-estuarine system. We show that while estuarine conditions in the system were fully established during the mid-Holocene highstand (~6.4 kyr BP), central basin facies sedimentation was focussed further inland before prograding with the lowering of base level and shifting of tidal influence as sea-level fell. Central basin facies sedimentation within northern Lake Albert occurred from 5.4 to 4.0 cal kyr BP at ~0.25 cm yr-1. The uppermost accumulation of this unit was eroded by continued reduction in base level until sea-level regression concluded at 3.5 cal kyr BP. Barrage and weir installation (1940 CE) re-initiated and expanded central basin facies sedimentation in the estuary (~0.32 cm yr-1). Recently deposited sediments exhibit geochemical markers of increased trophy and more frequent acid sulfate soil acidification, exposing human impacts on the estuary.

中文翻译：

---

南澳大利亚墨累河口的多阶段全新世演化

南澳大利亚墨累河河口呈现出以波浪为主的河口的典型形态，包括两个大型的浅水中央盆地湖泊——亚历山大湖和阿尔伯特湖。对河口湖沼学历史的有争议的解释以及围绕当前流域用水实践可持续性的不确定性，需要对该系统如何演变进行强有力的调查。在这里，我们结合了来自沉积岩心横断面的岩石地层学、地球化学和沉积学证据，以重建系统的沉积物填充历史。我们发现了系统历史上沉积物充填的多个阶段，与 (1) 河口和下游河道的低梯度形态，(2) 中晚期全新世海平面回归和 (3) 人为对河口系统的改造。我们表明，虽然系统中的河口条件在全新世中期高位 (~6.4 kyr BP) 期间完全建立，但中央盆地相沉积更集中于内陆，然后随着基准面的降低和潮汐影响作为海平面的转移而推进跌倒了。阿尔伯特湖北部的中央盆地相沉积发生在 5.4 至 4.0 cal kyr BP 约 0.25 cm yr-1 处。这个单元的最上面的积累被基础水平的持续下降侵蚀，直到海平面回归在 3.5 cal kyr BP 结束。拦河坝和堰安装（公元 1940 年）重新启动并扩大了河口中央盆地相沉积（~0.32 cm yr-1）。最近沉积的沉积物显示出营养增加的地球化学标记和更频繁的酸性硫酸盐土壤酸化，暴露了人类对河口的影响。