Geochemical characteristics of seabed sediments from Molloy Basin (ODP Site 909, in the Fram Strait) and the Nansen Basin (Arctic Ocean)

This study investigates the geochemical and mineralogical characteristics of Neogene deposits from the Fram Strait (ODP Site 909) and seabed sediments from the Nansen Basin to reconstruct sediment provenance and depositional conditions during the late Early Miocene (~13–16 million years ago, Ma) and compare them with modern sedimentation patterns. Major and trace element concentrations, rare earth element (REE) distributions, and clay mineral assemblages reveal long-term sediment transport pathways from Eurasian continental margins, particularly the Laptev and Kara Seas. The Miocene sediments exhibit low Mn:Al ratios and depleted REE concentrations, indicating sub-oxic depositional conditions and limited bottom water ventilation. In contrast, modern Nansen Basin sediments show higher Mn and REE levels, reflecting more oxic environments and increased glacial and fluvial input. Mineralogical data suggest a persistent dominance of smectite and kaolinite, with variations linked to climatic and tectonic shifts. The REE patterns, including Eu and Ce anomalies, provide insights into redox conditions and sediment provenance. These findings contribute to understanding Arctic Ocean evolution, sediment dynamics, and the establishment of geochemical baselines critical for future seabed resource assessments and climate impact monitoring. • Miocene sediments show low Mn:Al ratios, indicating sub-oxic conditions. • REE anomalies reveal sediment provenance and redox changes over time. • Fram Strait was in a transitional phase during the late stages of the Early Miocene. • First full REE dataset for Nansen Basin sets baseline for future monitoring.