Abstract Sediment budgets on wave-dominated coastlines are important in determining shoreline behaviour and are primarily inherited from geological-scale coastal evolutionary history. Sediment compartments provide a framework to conceptualise and investigate sediment budgets over a range of time and space scales. This study aims to assess the sediment budget for a secondary coastal compartment on the New South Wales (NSW) south coast ∼26 km in length and containing five adjacent but discrete Holocene coastal bay barriers: Barlings Beach, Broulee Beach, Bengello Beach, Moruya Heads Beach and Pedro Beach. Building on earlier morphostratigraphic studies, a new series of Optically Stimulated Luminescence (OSL) ages are presented for foredune ridge sequences at previously un-dated sites. Additional Ground Penetrating Radar (GPR) transects complement earlier stratigraphic datasets, and seamless topographic and bathymetric LiDAR datasets provide insight into subaerial coastal deposits and inner shelf morphology in this region. The results demonstrate that barriers within the compartment have two different sediment sources. The barriers are dominated by shoreface supply of quartz-rich sand transported onshore as shoreface morphology evolved towards equilibrium. Skeletal carbonate sand became an important component of the sediment budget for the northern Barlings and Broulee beaches after ∼3000 years ago. Shoreline progradation at Bengello Beach has been steady throughout the mid-to late- Holocene. Bengello contains the largest volume of Holocene sand and accreted at an average rate of 3.1 m3/m/yr (for the current shoreline length). The other barrier systems have experienced changes in sediment accumulation rate as their shorelines prograded seaward resulting in changes to their alongshore interconnectivity. Rapid filling of the Pedro Beach embayment by ∼4000 years ago initiated headland bypassing and northward sand transport to Moruya Heads Beach which only then commenced progradation. In contrast, as Broulee and Bengello Beaches prograded they converged in the lee of Broulee Island forming a tombolo which led to division of the former continuous shoreline into two. A marked increase in skeletal carbonate content at Broulee occurred after this separation attesting to the restriction of the southern quartz-sand source replaced by local carbonate production. This study emphasises the importance of understanding the long-term temporal variability in sediment budget and embayment interconnectivity in determining shoreline response to changing boundary conditions such as sea level and wave climate as well as contemporary anthropogenic influences.

中文翻译：

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澳大利亚东南部波浪主导的莫鲁亚海岸线的全新世演化：沉积物来源、运输速率和沿岸互连性

摘要 波浪主导的海岸线上的沉积物收支对于确定海岸线行为很重要，并且主要继承自地质尺度的海岸演化历史。沉积物隔室提供了一个框架来概念化和研究一系列时间和空间尺度的沉积物预算。本研究旨在评估新南威尔士州 (NSW) 南海岸约 26 公里长的次要沿海隔间的沉积物收支平衡，其中包含五个相邻但离散的全新世沿海海湾屏障：巴林斯海滩、布鲁利海滩、本杰洛海滩、莫鲁亚海德斯海滩和佩德罗海滩。在早期形态地层学研究的基础上，提出了一系列新的光激发光 (OSL) 年龄，用于以前未标注日期的地点的前缘脊序列。额外的探地雷达 (GPR) 断面补充了早期的地层数据集，无缝的地形和测深 LiDAR 数据集提供了对该地区地下沿海沉积物和内陆架形态的深入了解。结果表明隔间内的屏障有两种不同的沉积物来源。随着岸面形态向平衡方向发展，这些障碍主要由岸面供应的富含石英的沙子输送到岸上。大约 3000 年前，骨骼碳酸盐砂成为北部 Barlings 和 Broulee 海滩沉积物预算的重要组成部分。本杰洛海滩的海岸线进积在整个中晚期全新世一直稳定。本杰洛包含最大量的全新世砂，并且以平均 3.1 立方米/米/年的速度增生（就目前的海岸线长度而言）。其他屏障系统随着其海岸线向海的推进而经历了沉积物积累率的变化，从而导致其沿岸互连性发生变化。大约 4000 年前，佩德罗海滩海湾的快速填满​​开始了岬角绕过和向北运送沙子到莫鲁亚海德斯海滩，然后才开始进积。相比之下，随着 Broulee 和 Bengello 海滩的前移，它们在 Broulee 岛的背风处汇合，形成一个连环岛，导致以前连续的海岸线一分为二。Broulee 的骨骼碳酸盐含量在这次分离后显着增加，证明南部石英砂源的限制被当地的碳酸盐生产所取代。