Bulk geochemical and Rock-Eval data of sediment core IKU-7430/10-U-01 (Table 1)

The late Volgian (early \"Boreal\" Berriasian) sapropels of the Hekkingen Formation of the central Barents Sea show total organic carbon (TOC) contents from 3 to 36 wt%. The relationship between TOC content and sedimentation rate (SR), and the high Mo/Al ratios indicate deposition under oxygen-free bottom-water conditions, and suggest that preservation under anoxic conditions has largely contributed to the high accumulation of organic carbon. Hydrogen index values obtained from Rock-Eval pyrolysis are exceptionally high, and the organic matter is characterized by well-preserved type II kerogen. However, the occurrence of spores, freshwater algae, coal fragments, and charred land-plant remains strongly suggests proximity to land. Short-term oscillations, probably reflecting Milankovitch-type cyclicity, are superimposed on the long-term trend of constantly changing depositional conditions during most of the late Volgian. Progressively smaller amounts of terrestrial organic matter and larger amounts of marine organic matter upwards in the core section may have been caused by a continuous sea-level rise.

巴伦支海中部赫金根组的晚伏尔加阶（早“北方型”贝里亚斯阶）腐泥层总有机碳（TOC）含量为3至36重量百分比。总有机碳含量与沉积速率（SR）的关系以及高钼铝比表明沉积物形成于无氧底层水环境，且缺氧条件下的保存作用是有机碳大量积累的主要原因。岩石热解分析得到的氢指数异常高，有机质以保存良好的II型干酪根为特征。然而，孢子、淡水藻类、煤屑和烧焦的陆生植物残体的存在强烈表明沉积环境靠近陆地。晚伏尔加阶大部分时期内，短期波动（可能反映米兰科维奇型旋回）叠加在沉积条件持续变化的长期趋势之上。岩心剖面向上陆生有机质逐渐减少而海相有机质逐渐增加，这可能是持续海平面上升所致。