Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation.

Martin Jakobsson,Tom Flodén,Jan Backman,Rezwan Mohammad,Helen Coxall,Örjan Gustafsson,Laura Gemery,Johan Nilsson,Carina Johansson,Göran Björk,Thomas M Cronin,Nina Kirchner,Christian Stranne,Natalia Barrientos Macho,Kevin Jerram,Riko Noormets,A V Koshurnikov ,R A Ananiev ,Leif G Anderson ,A V Khortov ,Dennis Cherniykh ,Larry A Mayer ,Birgitta Eriksson ,Matt O’regan ,I P Semiletov

doi:10.1038/ncomms10365

Abstract

The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (∼140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening.

Highlights

The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago
Not all o1,000 m parts of the Lomonosov Ridge (LR) acted as pinning points, since a few sections are untouched by the ice shelf, but these may be explained by an uneven ice thickness (Fig. 6)
It may at first seem reasonable to limit this ice shelf to the Amerasian Basin and the LR, previously mapped lineations on the Yermak Plateau[16,33] fit well with the hypothesized flow pattern suggested by Hughes et al.[5]

Summary

Introduction

The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. On the Arlis Plateau, core SWERUS-L2-13-PC1 (13-PC1 on map, Fig. 2d, and on sub-bottom profile in Supplementary Fig. 3) recovered 6.14 m of sediment at a water depth of 1,119 m where the seafloor has been subjected to ice grounding.

Results

Conclusion