Timing of the local last glacial maximum in Terra Nova Bay, Antarctica defined by cosmogenic dating

Abstract

The Jangbogo Hills are erratic-covered landforms consisting of a series of benches that are parallel to the length of Campbell Glacier, northern Victoria Land, Antarctica. We sampled 41 erratic cobbles from six benches to reveal the exposure times of glacier erratics using in situ 10Be and 26Al. The erratics from the upper three benches yield exposure ages older than Marine Isotope Stage (MIS) 4, with most exposed since MIS 5. However, the lower three benches exhibit tight clusters of exposure ages that range from MIS 3 to the Holocene. Campbell Glacier underwent rapid downwasting during MIS 5, centered at 98.3 ka from its maximum position at the penultimate glacial maximum (PGM). This downwasting continued throughout the last glacial period, with a potential minor stagnation around a bench (~90m asl) between 35.4 and 17.0 ka. Our cosmogenic nuclides surface exposure dating results highlight three important points concerning the glacial history of Terra Nova Bay since the penultimate glacial maximum (PGM) in northern Victoria Land, Antarctica: 1) Campbell Glacier was thicker at the PGM than at the global last glacial maximum (LGM); 2) the local LGM occurred during MIS 4; and 3) the extent of Campbell Glacier during the global LGM (90 m) was much smaller than previously assumed (300e400 m). Hence, the previous view that the local LGM (MIS 4) in Victoria Land, Antarctica was synchronous with the global LGM (MIS 2) should be treated with caution.