Composition and Flux of Holocene Sediments on the Eastern Laptev Sea Shelf, Arctic Siberia

Abstract

A 467-cm-long core from the inner shelf of the eastern Laptev Sea provides a depositional history since 9400 cal yr. B.P. The history involves temporal changes in the fluvial runoff as well as postglacial sea-level rise and southward retreat of the coastline. Although the core contains marine fossils back to 8900 cal yr B.P., abundant plant debris in a sandy facies low in the core shows that a river influenced the study site until ∼8100 cal yr B.P. As sea level rose and the distance to the coast increased, this riverine influence diminished gradually and the sediment type changed, by 7400 cal yr B.P., from sandy silt to clayey silt. Although total sediment input decreased in a step-like fashion from 7600 to 4000 cal yr B.P., this interval had the highest average sedimentation rates and the greatest fluxes in most sedimentary components. While this maximum probably resulted from middle Holocene climate warming, the low input of sand to the site after 7400 cal yr B.P. probably resulted from further southward retreat of the coastline and river mouth. Since about 4000 cal yr B.P., total sediment flux has remained rather constant in this part of the Laptev Sea shelf due to a gradual stabilization of the depositional regime after completion of the Holocene sea-level rise.

Sources and characteristics of terrestrial carbon in Holocene-scale sediments of the East Siberian Sea

“…During the Pleistocene-Holocene transition the ESAS was flooded when the sea level rose rapidly (Lambeck et al, 2014;Mueller-Lupp et al, 2000). This global marine transgression started ∼ 20 000 cal yrs BP (Lambeck et al, 2014) and flooded the ESAS between ∼ 11 000 and ∼ 7000 cal yrs BP (Bauch et al, 2001a;Mueller-Lupp et al, 2000). The rate of the sea level rise was on the order of 1 cm yr −1 or more (Cronin et al, 2017;Stanford et al, 2011) in the early Holocene.…”

“…Post-glacial sea level rise with warming and wetting of the climate caused a major relocation of permafrost carbon from land to the Arctic Ocean (Bauch et al, 2001a;Tesi et al, 2016a). Today the period when the ESS is only partially covered with sea ice is on average 3 months per year, which is one of the reasons why the area remains fairly unstud- -1-58;Schlitzer, 2015).…”

“…The 14 C ages are shown in years BP with an age error (yrs) and as calibrated 14 C ages (cal yrs BP) with 2 standard deviations (±2σ ) of the individual 14 C dates. The calibration curve used was Marine13 (Reimer et al, 2013) and a R value of 50 ± 100 yrs (Bauch et al, 2001a 50 ± 100 years. Since there are no R values for the ESS in the literature, this R value was taken from a study in the Laptev Sea (Bauch et al, 2001a).…”

“…The increase in mean temperature coupled with sea level rise is thought to have profoundly destabilised PF-C and further released CO 2 to the atmosphere (Ciais et al, 2013;Crichton et al, 2016;Köh-ler et al, 2014;Tesi et al, 2016a). Several studies have suggested that there was a warming-coupled translocation of terrestrial carbon during the climate warming that ended the latest glacial period (e.g., Bauch et al, 2001a;Ciais et al, 2013;Mueller-Lupp et al, 2000;Tesi et al, 2016a) similar to what is predicted to happen as a consequence of the anthropogenic climate change (Barnhart et al, 2014;Vonk and Gustafsson, 2013).…”

“…Many of the previous Holocene timescale studies in the East Siberian Arctic Shelf (ESAS) have focused on the Laptev Sea (e.g., Bauch et al, 2001b;Mueller-Lupp et al, 2000;Tesi et al, 2016a). This study focuses on the East Siberian Sea (ESS), which has not yet been extensively studied, especially for the historical reconstruction of PF-C dynamics.…”