Deglacial sea level history of the East Siberian Sea and Chukchi Sea margins

Abstract

Abstract. ka) sea level history on the East Siberian continental shelf and upper continental slope was reconstructed using new geophysical records and sediment cores taken during Leg 2 of the 2014 SWERUS-C3 expedition. The focus of this study is two cores from Herald Canyon, piston core SWERUS-L2-4-PC1 (4-PC1) and multicore SWERUS-L2-4-MC1 (4-MC1), and a gravity core from an East Siberian Sea transect, SWERUS-L2-20-GC1 (20-GC1). Cores 4-PC1 and 20-GC were taken at 120 and 115 m of modern water depth, respectively, only a few meters above the global last glacial maximum (LGM; ∼ 24 kiloannum or ka) minimum sea level of ∼ 125-130 meters below sea level (m b.s.l.). Using calibrated radiocarbon ages mainly on molluscs for chronology and the ecology of benthic foraminifera and ostracode species to estimate paleodepths, the data reveal a dominance of river-proximal species during the early part of the Younger Dryas event (YD, Greenland Stadial GS-1) followed by a rise in river-intermediate species in the late Younger Dryas or the early Holocene (Preboreal) period. A rapid relative sea level rise beginning at roughly 11.4 to 10.8 ka (∼ 400 cm of core depth) is indicated by a sharp faunal change and unconformity or condensed zone of sedimentation. Regional sea level at this time was about 108 m b.s.l. at the 4-PC1 site and 102 m b.s.l. at 20-GC1. Regional sea level near the end of the YD was up to 42-47 m lower than predicted by geophysical models corrected for glacio-isostatic adjustment. This discrepancy could be explained by delayed isostatic adjustment caused by a greater volume and/or geographical extent of glacial-age land ice and/or ice shelves in the western Arctic Ocean and adjacent Siberian land areas.

Remobilization of Old Permafrost Carbon to Chukchi Sea Sediments During the End of the Last Deglaciation

“…Chukchi Shelf Sedimentation History 3.1.1. This study adds two new 14 C ages of benthic foraminifera, pooled from integrated depth sequences to the previously unconstrained section below 499 cm (12,100 ± 220 cal years BP; Cronin et al, 2017), between (i) 543-560 cm (13,020 ± 120 cal years BP) and (ii) 598-610 cm (12,830 ± 120 cal years BP; Table S1). Ten carbonaceous 14 C ages of mollusk shells constitute the basis of the chronology for this core, which has been presented and discussed in previous studies Jakobsson et al, 2017).…”

“…The 4-PC1 Chronology and Timing of the Late Deglaciation Core 4-PC1 provides a well-dated record of regional sedimentation history with a basal age of 13,120 years at 613 cm core depth (Figure 3). The age model described by Cronin et al (2017) was here revised to include these new 14 C dates. This study adds two new 14 C ages of benthic foraminifera, pooled from integrated depth sequences to the previously unconstrained section below 499 cm (12,100 ± 220 cal years BP; Cronin et al, 2017), between (i) 543-560 cm (13,020 ± 120 cal years BP) and (ii) 598-610 cm (12,830 ± 120 cal years BP; Table S1).…”

“…We extended the earlier-published 4-PC1 age model by Cronin et al (2017) using 14 C-dated benthic foraminifera (mainly Elphidium sp.) 14 C and 13 C Analyses 2.3.1.…”

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

“…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. The sampling site of the sediment core investigated in this study was flooded around 11 000 cal yrs BP (Lambeck et al, 2014).…”

The De Long Trough: a newly discovered glacial trough on the East Siberian continental margin

“…Radiocarbon dates and calibrations from sediment cores 20-GC1, 23-GC1 and 24-GC1. All dates were calibrated with the Marine13 calibration curve (Reimer et al, 2013), with R = 50 ± 100 years for 20-GC1 (Cronin et al, 2017) and R = 0 years for 23-GC1 and 24-GC1. are no prominent morphological seafloor features distinguishable along the transect, where a single swath of multibeam bathymetry was collected (Fig.…”