Amino acid racemization (AAR) geochronology is a powerful tool for dating Quaternary marine sediments across the globe, yet its application to Arctic Ocean sediments has been limited. Anomalous rates of AAR in foraminifera from the central Arctic were reported in previously published studies, indicating that either the rate of racemization is higher in this area, or inaccurate age models were used to constrain the sediment ages. This study investigates racemization rates in foraminifera from three well-dated sediment cores taken from the Yermak Plateau during the 2015 TRANSSIZ (TRansitions in the Arctic Seasonal Sea Ice Zone) expedition on RV Polarstern. D and L isomers of the amino acids aspartic acid (Asp) and glutamic acid (Glu) were separated in samples of the planktic foraminifer Neogloboquadrina pachyderma and the benthic species Cassidulina neoteretis to quantify the extent of racemization. In total, 241 subsamples were analysed, extending back to marine oxygen isotope stage (MIS) 7. Two previously published power functions, which relate the extent of racemization of Asp and Glu in foraminifera to sample age are revisited, and a comparison is made between the ages predicted by these calibrated age equations and independent geochronological constraints available for the cores. Our analyses reveal an excellent match between ages predicted by a global compilation of racemization rates for N. pachyderma and confirm that a proposed Arctic-specific calibration curve is not applicable at the Yermak Plateau. These results generally support the rates of AAR determined for other cold bottom water sites and further highlight the anomalous nature of the purportedly high rate of racemization indicated by previous analyses of central Arctic sediments.

Establishing a solid chronological framework for Arctic marine sediments is a critical first step towards glacial and palaeoceanographic reconstructions. However, this has historically been more challenging than elsewhere in the world, and often results in core chronologies and subsequent paleoenvironmental reconstructions being questioned and overturned. Optically stimulated luminescence (OSL) dating provided important constraints on late Quaternary ages for central Arctic marine sediments, and has considerable potential to underpin chronologies in other parts of the Arctic Ocean. This study applies OSL and infrared stimulated luminescence (IRSL) geochronology to multi-grain quartz and feldspar samples from a sediment core collected from the Lomonosov Ridge off the Siberian shelf during the 2014 SWERUS-C3 Expedition. Testing and advancing the proposed chronology of late Quaternary sediments in this part of the Arctic is essential to better constrain the timing of ice sheet growth on the Siberian Arctic shelf and subsequent ice shelf development in the Arctic Ocean. The results of luminescence dating support a pre-Eemian age for extensive ice grounding and scouring of the southern Lomonosov Ridge. Furthermore, we combine the OSL ages with data from rock magnetic measurements and propose an age-depth model for cores in this region. As in other areas in the Arctic, magnetic grain size/mineralogy profiles resemble the global oxygen isotope curve and may have the potential to be a dating tool. This can be tested and further refined in future studies that obtain longer sedimentary archives. Our results also indicate that changes in the inclination of the natural remanent magnetisation do not reflect geomagnetic field variation in the investigated sediment cores.