Paleo-shorelines on continental shelves give insights into the complex development of coastlines during sealevel cycles. This study investigates the geologic development of the Limpopo Shelf during the last sealevel cycle using multichannel seismic and acoustic datasets acquired on the shelf in front of the Limpopo River mouth. A detailed investigation of seismic facies, shelf bathymetry, and a correlation to sea level revealed the presence of numerous submerged shorelines on the shelf. These shorelines are characterized by distinct topographic ridges and are interpreted as coastal dune ridges that formed in periods of intermittent sealevel still-/slowstand during transgression. The shorelines are preserved due to periods of rapid sealevel rise (melt water pulses) that led to the overstepping of the dune ridges as well as due to early cementation of accumulated sediments that increased the erosive resistance of the ridges. The high along-shelf variability of the submerged dune ridges is interpreted as a result of pre-existing topography affecting shoreline positions during transgression. The pre-existing topography is controlled by the underlying sedimentary deposits that are linked to varying fluvial sediment input at different points on the shelf. The numerous prominent submerged dune ridges form barriers for the modern fluvial sediment from the Limpopo River and dam sediment on the inner shelf. They may also facilitate along-shelf current-induced sediment transport.

中文翻译：

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上一次海平面循环期间林波波大陆架（莫桑比克南部）的地质发展

大陆架上的古海岸线提供了对海平面循环期间海岸线复杂发展的见解。本研究使用在林波波河河口前的陆架上采集的多通道地震和声学数据集，调查了上次海平面循环期间林波波陆架的地质发展。对地震相、陆架水深测量以及与海平面的相关性的详细调查显示，陆架上存在许多淹没的海岸线。这些海岸线以独特的地形脊为特征，被解释为海岸沙丘脊，形成于海侵期间间歇性海平面静止/缓慢停顿时期。由于海平面快速上升（融化水脉冲）导致沙丘脊越过，以及由于堆积沉积物的早期胶结增加了沙丘的侵蚀阻力，海岸线得以保留。淹没沙丘脊沿陆架的高度变化被解释为预先存在的地形在海侵期间影响海岸线位置的结果。预先存在的地形受下伏沉积沉积物控制，这些沉积物与陆架上不同点的不同河流沉积物输入有关。许多突出的淹没沙丘脊为来自林波波河的现代河流沉积物和内陆架上的水坝沉积物形成屏障。它们还可能促进沿陆架电流引起的沉积物运输。