Atmospheric gas records from Taylor Glacier, Antarctica, reveal ancient ice with ages spanning the entire last glacial cycle

Abstract

Abstract.Old ice for paleo-environmental studies, traditionally accessed through deep core drilling on domes and ridges on the large ice sheets, can also be retrieved at the surface from ice sheet margins and blue ice areas. The practically unlimited amount of ice available at these sites satisfies a need in the community for studies of trace components requiring large sample volumes. For margin sites to be useful as ancient ice archives, the ice stratigraphy needs to be understood and age models need to be established. We present measurements of trapped gases in ice from Taylor Glacier, Antarctica, to date the ice and assess the completeness of the stratigraphic section. Using δ 18 O of O 2 and methane concentrations, we unambiguously identify ice from the last glacial cycle, covering every climate interval from the early Holocene to the penultimate interglacial. A high-resolution transect reveals the last deglaciation and the Last Glacial Maximum (LGM) in detail. We observe large-scale deformation in the form of folding, but individual stratigraphic layers do not appear to have undergone irregular thinning. Rather, it appears that the entire LGM-deglaciation sequence has been transported from the interior of the ice sheet to the surface of Taylor Glacier relatively undisturbed. We present an age model that builds the foundation for gas studies on Taylor Glacier. A comparison with the Taylor Dome ice core confirms that the section we studied on Taylor Glacier is better suited for paleo-climate reconstructions of the LGM due to higher accumulation rates.

Is the Noble Gas‐Based Rate of Ocean Warming During the Younger Dryas Overestimated?

“…Sixteen ice core samples from Taylor Glacier covering 13.4–11.0 ka BP were collected along a previously established sampling line, which contains a well‐dated, high‐resolution record of the last deglaciation (Baggenstos et al, ). Samples were analyzed for isotopes of nitrogen, argon, and krypton and Kr/N 2 , Xe/N 2 , and Xe/Kr following Bereiter, Kawamura, et al ().…”

“…Because of the important implications of the rapid YD1 MOT warming, we sought to replicate this MOT change with another ice core record. We analyzed samples from Taylor Glacier, Antarctica, a blue ice area where ice from the last glacial cycle can be found in abundance (Baggenstos et al, ). Importantly, the air in Taylor Glacier ice is enclosed entirely in the form of bubbles and lacks clathrates due to the relatively shallow depth of the glacier, while WD is a deep ice core in which the Younger Dryas is within fully clathrated ice, approximately 400 to 500 m below the bubble‐clathrate transition zone (BCTZ; Fitzpatrick et al, ).…”

Spatial pattern of accumulation at Taylor Dome during Marine Isotope Stage 4: stratigraphic constraints from Taylor Glacier

“…Blue ice areas, where a combination of glacier flow and high ablation rates bring old ice layers to the surface, offer relatively easy access to large samples and can supplement traditional ice cores (Bintanja, 1999;Sinisalo and Moore, 2010). Blue ice areas often have complex depth-age and distance-age relationships disrupted by folding and thinning of stratigraphic layers (e.g., Petrenko et al, 2006;Baggenstos et al, 2017). Taking full advantage of blue ice areas requires precise age control and critical examination of the glaciological context in which they form.…”

“…Effective techniques for dating ablation zone ice include matching globally well-mixed atmospheric trace gas records (e.g., CH 4 , CO 2 , δ 18 O atm , N 2 O) and correlating glaciochemical records (e.g., δ 18 O ice , Ca 2+ , insoluble particles) with existing ice core records with precise chronologies Schilt et al, 2014;Petrenko et al, 2008Petrenko et al, , 2016Schaefer et al, 2009;Baggenstos et al, 2017;Aarons et al, J. A. Menking et al: Stratigraphic constraints from Taylor Glacier 2017).…”

“…A number of blue ice areas have provided useful paleoclimate archives including Pakitsoq, Greenland, for the Younger Dryas-Preboreal transition Schaefer et al, 2009Schaefer et al, , 2006, Allan Hills, Victoria Land, Antarctica, for ice 90-250 ka and > 1 Ma (Spaulding et al, 2013;Higgins et al, 2015), Mt. Moulton, Antarctica, for the last interglacial (Korotkikh et al, 2011), the Patriot Hills, Horseshoe Valley, Antarctica, for ice from the last glacial termination (Fogwill et al, 2017), and Taylor Glacier, McMurdo Dry Valleys, Antarctica, for ice spanning the last glacial termination and MIS 3 Schilt et al, 2014;Baggenstos et al, 2017;Petrenko et al, 2017). Taylor Glacier is particularly well suited for paleoclimate reconstructions because of the excellent preservation of near-surface ice, large age span, and continuity of the record (Buizert et al, 2014;Baggenstos, 2015;Baggenstos et al, 2017).…”