Volume 379: Amundsen Sea West Antarctic Ice Sheet History

Abstract

Introduction 3 Background 6 Objectives 7 Operations plan/drilling strategy 7 Site summaries 12 Preliminary scientific assessment 17 References from the Amundsen Sea Embayment westward along the Marie Byrd Land margin to the easternmost Ross Sea through a connecting network of seismic lines.

Evidence for a Highly Dynamic West Antarctic Ice Sheet During the Pliocene

“…GOHL ET AL. (Gohl et al, 2021;Wellner et al, 2021a). Diatom abundance in smear slides is categorized as barren (B; 0%), trace (T; <2%), rare (R; 2%-5%), few (F; 5%-10%), common (C; 10%-20%), abundant (A; 20%-40%), and very abundant (V; 40%-60%).…”

“…The high sedimentation rates on Resolution Drift during the early Pliocene documented by the Expedition 379 records are presumably related to major shelf progradation during this period, which resulted in high sediment supply to the rise. (Gohl et al, 2021;Wellner et al, 2021a). Diatom abundance in smear slides is categorized as barren (B; 0%), trace (T; <2%), rare (R; 2%-5%), few (F; 5%-10%), common (C; 10%-20%), abundant (A; 20%-40%), and very abundant (V; 40%-60%).…”

“…Recently, shelf sediments in the ASE were drilled with the MARUM-MeBo70 sea-bed drilling device in 2017, recovering sedimentary rocks of Cretaceous to Oligocene-Miocene age (Gohl et al, 2017;Klages et al, 2020). The almost continuous sequences at IODP Expedition 379 Sites U1532 and U1533 on the continental rise (Gohl et al, 2021;Wellner et al, 2021aWellner et al, , 2021b span the latest Miocene to Holocene with high core recovery rates of 90% and 70%, respectively (Figure 1). Site U1532 is located near the crest of Resolution Drift (Figure S1) and penetrated down to 794 m depth below the seafloor, exhibiting sedimentation rates of up to 61 cm kyr −1 within the Pliocene.…”

“…In order to address past ice-sheet dynamic processes in the Amundsen Sea sector, we analyzed seismic lines across the ASE shelf with direct connection to the two drill sites of the International Ocean Discovery Program (IODP) Expedition 379 (Gohl et al, 2021) on the continental rise (Figure 1). The ASE shelf is characterized by large cross-shelf paleo-ice stream troughs, such as Pine Island Trough (PIT) with its outer shelf western (PITW) and eastern (PITE) branches, Dotson-Getz Trough (DGT), and Abbot-Cosgrove Trough (ACT).…”

“…The sediments at sites U1532 and U1533 contain unique records to study the cyclicity of WAIS advance and retreat. In particular, Site U1532 contains a sequence of Pliocene sediments with an almost complete paleomagnetic record for constraining very high resolution, suborbital scale climate variability, thus providing an opportunity to better develop climate records for the sparsely sampled pre-Pleistocene interval in the Amundsen Sea (Gohl et al, 2021).…”