Holocene deglaciation and glacier readvances on the Fildes Peninsula and King George Island (Isla 25 de Mayo), South Shetland Islands, NW Antarctic Peninsula

• Main Authors: Heredia Barión, P, Roberts, SJ, Spiegel, C, Binnie, SA, Wacker, L, Davies, J, Gabriel, I, Jones, Vivienne, Blockley, S, Pearson, EJ, Foster, L, Davies, SJ, Roland, TP, Hocking, E, Bentley, MJ, Hodgson, DA, Hayward, CL, McCulloch, RD, Strelin, JA, Kuhn, G
• Format: Report
• Language: English
• Published: Earth ArXiv 2022
• Subjects: Palaeoenvironmental change; chronology; geomorphology; diatoms; tephra; Southern Hemisphere Westerly Winds; South Shetland Islands; Antarctic; Antarctic Peninsula; King George Island; Fildes; Fildes peninsula; 25 de Mayo; isla 25 de Mayo; Antarc*; Ice cap; Isla 25 de Mayo
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10169974/1/Jones_Holocene%20deglaciation%20and%20glacier%20readvances%20on%20the%20Fildes%20Peninsula%20and%20King%20George%20Island_pre-print2.pdf; https://discovery.ucl.ac.uk/id/eprint/10169974/

To provide insights into glacier-climate dynamics of the South Shetland Islands (SSI), NW Antarctic Peninsula, we present a new deglaciation and readvance model for the Bellingshausen Ice Cap (BIC) on Fildes Peninsula and for King George Island/Isla 25 de Mayo (KGI) ~62°S. Deglaciation on KGI began after c. 15 ka cal BP and had progressed to within present-day limits on the Fildes Peninsula, its largest ice-free peninsula, by c. 6.6–5.3 ka cal BP. Probability density phase analysis of chronological data constraining Holocene glacier advances on KGI revealed up to eight 95% probability ‘gaps’ during which readvances could have occurred. These are grouped into four stages – Stage 1: a readvance and marine transgression, well-constrained by field data, between c. 7.4–6.6 ka cal BP; Stage 2: four probability ‘gaps’, less well-constrained by field data, between c. 5.3–2.2 ka cal BP; Stage 3: a well-constrained but restricted ‘readvance’ between c. 1.7–1.5 ka; Stage 4: two further minor ‘readvances’, one less well-constrained by field data between c. 1.3–0.7 ka cal BP (68% probability), and a ‘final’ well-constrained ‘readvance’ after <0.7 ka cal BP. The Stage 1 readvance occurred as colder and more negative Southern Annular Mode (SAM)-like conditions developed, and marginally stronger/poleward shifted westerly winds led to more storms and precipitation on the SSI. Readvances after c. 5.3 ka cal BP were possibly more frequent, driven by reducing spring/summer insolation at 62°S and negative SAM-like conditions, but weaker (equatorward shifted) westerlies over the SSI led to reduced storminess, restricting readvances within or close to present day limits. Late Holocene readvances were anti-phased with sub-aquatic moss layers in lake records unaffected by glaciofluvial inputs. Retreat from ‘Neoglacial’ glacier limits and the recolonisation of lakes by sub-aquatic moss in the post-bomb era (>1950 CE) is associated with recent warming/more positive SAM-like conditions.