Abstract The Quaternary stratigraphy of many coastal areas in Southeast Asia is poorly understood. Developing a detailed framework is important as many coastal cities are built on these unconsolidated coastal-marine sediments. This study reviews the current understanding of Quaternary deposits in the Kallang River Basin, Singapore, using 161 boreholes to create 14 cross-sections and a 3D geological model. The dataset is augmented with a ~38.5 m long sediment core obtained from Marina South (1.2726°N, 103.8653°E), and a previous record from Geylang (1.3137°N; 103.8917°E), to provide age constraints and stratigraphic reference. A new Quaternary stratigraphic framework for Singapore is presented here, constrained by new radiocarbon and Optically Stimulated Luminescence (OSL) dating, and identify palaeo-features that record the geomorphic and sedimentary evolution of the basin. Fluvial deposits of Pleistocene age are uncomfortably overlain by littoral/tidal sands and subsequently marine clay possibly during Marine Isotope Stage (MIS) 5e (~125 ka BP). Subsequent subaerial exposure and weathering of the marine clay during the last interglacial produced a ‘stiff clay’ layer. The stiff clay is unconformably overlain by Holocene transgressive sands and peats from ~9.5 ka BP, followed by marine clays with a maximum basal age of ~9.2 ka BP. Regressive sandy/peat units were subsequently deposited beginning ~6 ka BP. Here the new Quaternary stratigraphic framework for Singapore is presented, as well as provide important constraints on the regional sea-level history and geomorphological evolution of Singapore's southern coast from MIS 5e to present. The work also highlights the complexities of geoengineering work in such subsurface terranes.

中文翻译：

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新加坡加冷河流域的新第四纪地层：对新加坡城市发展和岩土工程的影响

摘要 东南亚许多沿海地区的第四纪地层学知之甚少。制定详细的框架很重要，因为许多沿海城市都建立在这些松散的沿海-海洋沉积物上。本研究回顾了目前对新加坡加冷河流域第四纪矿床的理解，使用 161 个钻孔创建了 14 个横截面和一个 3D 地质模型。该数据集增加了从 Marina South (1.2726°N, 103.8653°E) 获得的约 38.5 m 长的沉积岩芯，以及来自芽笼 (1.3137°N; 103.8917°E) 的先前记录，以提供年龄限制和地层参考。此处介绍了新加坡的新第四纪地层框架，受新放射性碳和光激发光 (OSL) 测年的限制，并确定记录盆地地貌和沉积演化的古特征。更新世时代的河流沉积物令人不舒服地覆盖在沿海/潮汐沙子上，随后可能在海洋同位素阶段 (MIS) 5e (~125 ka BP) 期间覆盖着海洋粘土。随后在最后一次间冰期期间海底暴露和海相粘土的风化产生了“硬粘土”层。坚硬的粘土不整合地覆盖在~9.5 ka BP 的全新世海侵砂和泥炭上，其次是海相粘土，其最大基础年龄为~9.2 ka BP。随后在~6 ka BP 开始沉积了退化的砂质/泥炭单元。这里介绍了新加坡新的第四纪地层框架，并为新加坡的区域海平面历史和地貌演变提供了重要的约束条件。从 MIS 5e 到现在的南部海岸。这项工作还强调了在此类地下地层中地球工程工作的复杂性。