Abundance and opal input of radiolarian species of two sediment cores from the Atlantic sector of the Southern Ocean

Radiolarian-based paleoceanographic reconstructions generally use the abundance of selected radiolarian species. However, the recent focus on the opal flux and the development of isotope measurements in biogenic opal and the organic matter embedded in it demands a better knowledge of the origin of the opal. We present here an estimation of the opal content of the skeleton of 63 radiolarian species from two sites in the Southern Ocean. The skeletons are modelled as associations of simple geometrical shapes, and the volume thus obtained is combined with opal density to obtain the amount of opal. These data are, thus, used to determine the most important opal carriers in the radiolarian assemblage in both cores.基于放射虫(Radiolarian)的古海洋学重建研究通常采用选定放射虫物种的丰度数据。然而，当前学界对蛋白石通量(opal flux)的关注，以及生物成因蛋白石(biogenic opal)及其包埋有机质的同位素测试技术的发展，要求我们更深入地厘清蛋白石的成因。本研究针对南大洋(Southern Ocean)两个站位的63种放射虫，估算其骨骼的蛋白石含量。研究将放射虫骨骼建模为简单几何形状的组合，通过计算得到的体积结合蛋白石密度，即可推算出蛋白石的总含量。据此，本研究明确了两个岩芯中放射虫组合(radiolarian assemblage)内最主要的蛋白石承载物种。