Carbon and Sulphur concentrations of sediments from Peru, Oman and Benguela upwelling environments

Abundances of organic carbon, sulfur, and reactive iron in sediments of three upwelling environments (Peru, Oman and Benguela) suggest that organic carbon/reduced sulfur ratios (C/S-ratios) in this category of marine sediments deviate considerably from previously established empirical ratios in normal marine sediments. To clarify the discrepancies, we investigated those components of the diagenetic system that limit the formation of pyrite: sulfate concentrations and reduction rates in pore waters, availability of reactive iron, and the quantity and quality of organic matter. All three limitations are evident in our sample pools. The results suggest that C/S-ratios in recent and fossil marine sediments rich in organic matter may be unsuitable as paleoenvironmental indicators.对秘鲁、阿曼和本格拉三处上升流环境沉积物中的有机碳、硫及活性铁丰度进行分析后发现，该类海洋沉积物的有机碳/还原硫比值（C/S-ratios）与常规海洋沉积物中已确立的经验比值存在显著偏离。为厘清这一差异，我们针对限制黄铁矿形成的成岩系统组分展开了研究，包括孔隙水中的硫酸盐浓度与还原速率、活性铁的可利用性，以及有机质的数量与质量。上述三类限制因素在本次研究的样本集合中均有体现。研究结果表明，富含有机质的现代及化石海洋沉积物中的C/S比值，或不适宜作为古环境指示指标。