Lithological and chemical composition, stages of sediment accumulation, and sedimentation rates in Core PSh24-2537, West Gotland Basin, Baltic Sea

We studied the grain-size, mineral and chemical compositions, physical properties, radiocarbon age, spore-pollen spectra, and diatom composition in sediments from Core PSh24-2537 sampled in the West Gotland Basin. Four lithological-stratigraphic units were distinguished: varved clays of the Baltic Ice Lake, black and black-gray (sulfide) clays of the Yoldian Sea, gray clays of Ancylus Lake, and greenish-gray sapropel-like littorine and post-littorine silts of the marine stage of Holocene. These units differ from each other both in their matter composition and in plant remains. In the littorine silts organic carbon concentra¬tion reached from 1.5 to 10.35%. Conditions of sediment accumulation and the stages of evolution of the West Gotland Basin over the post-glacial time are characterized.

本研究针对采自哥特兰西部盆地（West Gotland Basin）的PSh24-2537岩芯沉积物，开展了粒度组成、矿物与化学成分、物理性质、放射性碳年代（radiocarbon age）、孢粉谱（spore-pollen spectra）以及硅藻组成（diatom composition）的分析。研究共识别出4个岩石地层（lithological-stratigraphic）单元：分别为波罗的海冰湖（Baltic Ice Lake）纹泥黏土、约尔迪亚海（Yoldian Sea）黑色及黑灰色（硫化物）黏土、安基卢斯湖（Ancylus Lake）灰色黏土，以及全新世（Holocene）海相阶段的灰绿色类腐泥质潮间带及潮间带后粉砂。上述单元不仅在物质组成上存在显著差异，其赋存的植物残体特征亦各不相同。在潮间带粉砂中，有机碳浓度（organic carbon concentration）可达1.5%至10.35%。本研究同时阐明了冰川后时期哥特兰西部盆地的沉积物沉积环境及其演化阶段。