Refining the age-depth model of a marine sediment record in the Laptev Sea using Beryllium-10

In order to correctly determine leads and lags in the climate system and compare different proxy records over long time periods, it is important to build robust chronologies that can provide the temporal foundation for paleoclimate correlations between marine, terrestrial and ice-core records. One of the main challenges for building reliable radiocarbon-based chronologies in the marine realm is to estimate the regional marine radiocarbon reservoir age correction. Estimates of the local marine reservoir effect, ΔR, during the deglaciation can be obtained by ¹⁴C-independent dating methods such as synchronization to other well-dated archives. The cosmogenic radionuclide ¹⁰Be provides such a synchronization tool. Its atmospheric production rate is globally modulated by changes in the cosmic ray flux caused by changes in solar activity and geomagnetic field strength. The resulting variations in the meteoric fallout of¹⁰Be are recorded in sediments and ice cores and can thus be used for their synchronization.

In this study we use for the first time the authigenic ¹⁰Be/⁹Be record of a Laptev Sea sediment core and synchronize it to the ¹⁰Be records from absolutely dated ice cores. Based on the resulting absolute chronology, the ΔR  was then estimated for the Laptev Sea during the deglaciation. The deglacial estimate for the benthic ΔR value for the Laptev Sea is 345±60 ¹⁴C years, corresponding to a marine reservoir age of 864±90 ¹⁴C years. We discuss the obtained ΔR in comparison to modern ΔR estimates from the literature and its consequences for the age-depth model. Our refined age-depth model can be used as a reference for the Laptev Sea and the wider Siberian regions of the Arctic Ocean.