The deglaciation of Barton Peninsula (King George Island, South Shetland Islands, Antarctica) based on geomorphological evidence and lacustrine records

Abstract

Barton Peninsula is an ice-free area located in the southwest corner of King George Island (South Shetland Islands, Antarctica). Following the Last Glacial Maximum, several geomorphological features developed in newly exposed ice-free terrain and their distribution provide insights about past environmental evolution of the area. Three moraine systems are indicative of three main glacial phases within the long-term glacial retreat, which also favoured the development of numerous lakes. Five of these lakes were cored to understand in greater detail the pattern of deglaciation through the study of lacustrine records. Radiocarbon dates from basal lacustrine sediments enabled the reconstruction of the chronology of Holocene glacial retreat. Tephra layers present in lake sediments provided additional independent age constraints on environmental changes based on geochemical and geochronological correlation with Deception Islandderived tephra. Shrinking of the Collins Glacier exposed the southern coastal fringe of Barton Peninsula at 8 cal ky BP. After a period of relative stability during the mid-Holocene, the ice cap started retreating northwards after 3.7 cal ky BP, confining some glaciers within valleys as shown by moraine systems. Lake sediments confirm a period of relative glacial stability during the last 2.4 cal ky BP.

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

“…ka BP - Bentley et al (2009);1250-950 CE -Mann et al (2009. No evidence of substantial glacial readvance exists on KGI or the northern AP during the MCA (Charman et al, 2018;Emslie et al, 2019;Oliva et al, 2019;Kaplan et al, 2020), and marine sediment records from Maxwell Bay and Potter Cove imply no substantial increases in sea-ice at this time (Figure 5D) (Milliken et al, 2009;Monien et al, 2011). Increased fine-grained sedimentation in Potter Cove during the MCA has been linked to warmer conditions, including warmer sea surface temperatures from the western AP (Milliken et al, 2009;Hass et al, 2010;Watcham et al, 2011;Etourneau et al, 2013).…”

“…Field-based reconstructions of Antarctic ice sheet and ice cap deglaciation after the Last Glacial and into the Holocene are important components of ice sheet models used to examine the impact of future ice-melt on rates of regional-global sea-level change (Sugden and Clapperton, 1977;Ó Cofaigh et al, 2014;Lindow et al, 2014;Simms et al, 2018Simms et al, , 2019Kaplan et al, 2020;Nývlt et al, 2020;Oliva et al, 2020). Despite numerous studies, the Early to Mid-Holocene deglaciation and the number, timing, and extent of Mid-to Late Holocene glacier readvances on the northern Antarctic Peninsula (NAP) and South Shetland Islands (SSI) remains debated (Hall, 2007(Hall, , 2009Simms et al, 2011;Watcham et al, 2011;Simms et al, 2011Simms et al, , 2012Ó Cofaigh et al, 2014;Emslie et al, 2019;Oliva et al, 2019).…”

Inventário De Lagos Glaciais Nas Ilhas Nelson E Rei George, Antártica Marítima

“…Desta forma, os lagos das ilhas representam uma condição de estogagem continental de água e sedimentos, que, na sua maioria, não vão para o mar e portanto não contribuem com o recente aumento médio dos níveis dos mares. A dinâmica sedimentar destes lagos traz informações paleoclimáticas importantes, como destacado por Oliva et al (2019). Estes lagos de água doce são habitats de diversas espécies e assembléia de fungos, como evidenciada por Rosa (2019).…”

“…A maioria destes se encontram distantes da geleira e podem ser endorréicos. Estes lagos não são recentes,Oliva et al, (2019) estudaram cinco lagos nesta Península para investigar a deglaciação holocênica. Quanto à declividade, os lagos também se formam em áreas com menor declividade, entre 0-20% (Tabela 01).Tabela 01 -Características dos lagos nas penínsulas da ilha Rei George.…”

Detection and Delineation of Sorted Stone Circles in Antarctica

“…The sites selected for developing the surveys are located in the ice-free areas of Barton Peninsula (62 • 14'S; 58 • 46'W) in King George Island, the largest one of the South Shetlands in Antarctica (Figure 2 left). This peninsula has an area of about 10 km 2 that started to be exposed about 8000 years ago after glacial retreat [32]. It shows a rugged topography, with a wide and gentle slope in the central area, ranging from about 90 to 190 m a.s.l., where the majority of stone circles fields are found [33].…”