Sedimentology at the continental margin of the southern Weddell Sea

During four expeditions with RV \"Polarstern\" at the continental margin of the southern Weddell Sea, profiling and geological sampling were carried out. A detailed bathymetric map was constructed from echo-sounding data. Sub-bottom profiles, classified into nine echotypes, have been mapped and interpreted. Sedimentological analyses were carried out on 32 undisturbed box grab surface samples, as well as on sediment cores from 9 sites. Apart from the description of the sediments and the investigation of sedimentary structures on X-radiographs the following characteristics were determined: grain-size distributions; carbonate and Corg content; component distibutions in different grain-size fractions; stable oxygen and carbon isotopes in planktic and, partly, in benthic foraminifers; and physical properties. The stratigraphy is based On 14C-dating, oxygen isotope Stages and, at one site, On paleomagnetic measurements and 230Th-analyses The sediments represent the period of deposition from the last glacial maximum until recent time. They are composed predominantly of terrigenous components. The formation of the sediments was controlled by glaciological, hydrographical and gravitational processes. Variations in the sea-ice coverage influenced biogenic production. The ice sheet and icebergs were important media for sediment transport; their grounding caused compaction and erosion of glacial marine sediments on the outer continental shelf. The circulation and the physical and chemical properties of the water masses controlled the transport of fine-grained material, biogenic production and its preservation. Gravitational transport processes were the inain mode of sediment movements on the continental slope. […]本数据集基于‘极星号’（RV "Polarstern"）科研调查船在南威德尔海大陆边缘开展的4次科考航次，完成了剖面测量与地质取样工作。研究团队利用回声测深数据绘制了高精度海底地形地图。针对划分为9种回声类型（echotypes）的海底次表层剖面，完成了制图与解译工作。针对32份未受扰动的箱式采泥表层样品，以及9个站位的沉积物岩芯，开展了沉积学分析。除对沉积物进行描述，并通过X射线照相底片分析沉积构造外，本研究还测定了多项参数：粒度分布、碳酸盐与有机碳（Corg）含量、不同粒级组分的分布特征、浮游有孔虫（部分站位同步分析底栖有孔虫）中的稳定氧、碳同位素组成，以及沉积物物理性质。地层年代框架基于14C测年、氧同位素阶段划分，其中一个站位的地层还结合了古地磁测量与钍-230（230Th）分析结果确定。本次研究涉及的沉积物沉积时代覆盖末次冰盛期至现代，以陆源组分为主。沉积物的形成受冰川学、水文学与重力作用过程共同调控：海冰覆盖范围的变化显著影响生物产率；冰盖与冰山是沉积物搬运的重要载体，其搁浅作用会导致大陆架外缘的冰川海相沉积物发生压实与侵蚀；水团的环流过程及其物理、化学性质调控了细粒物质的搬运、生物产率及其保存状态；重力搬运过程则是大陆坡沉积物运移的主要方式。[...]