GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 304-6
Presentation Time: 3:05 PM


GOEHRING, Brent M.1, NICHOLS, Keir1, BALCO, Greg2 and TODD, Claire3, (1)Dept. of Earth and Environmental Sciences, Tulane University, 6823 St Charles Ave, New Orleans, LA 70118, (2)Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, (3)Geosciences, Pacific Lutheran University, Tacoma, WA 98447,

The low-erosive nature of the Antarctic ice sheet makes using long-lived cosmogenic nuclides potentially challenging due the preservation of inherited nuclides in paleo-ice sheet reconstructions. In situ carbon-14 (14C) potentially avoids the challenge of inheritance. We present measurements of in situ carbon-14 from two vertical transects in the outer Ross Sea, Antarctica, adjacent to Tucker Glacier and Aviator Glacier. Our 14C results elucidate the thinning/retreat history of this sector of the West Antarctic ice sheet (WAIS) as they are not influenced by inheritance. Major thinning of the Ross Sea sector of the WAIS is observed at ~12 ka at Tucker Glacier (northern site). After ~12 ka, thinning slowed and progressed monotonically to the present ice surface elevation. In contrast, at Aviator Glacier (southern site), thinning is relatively monotonic through the past 12 ka, with slightly faster thinning occurring at ~7 ka. Absent at both sites, though, is evidence for the maximum Last Glacial Maximum extent, which would be expressed by a break in the age-elevation slope from unsaturated to saturated 14C values. We are presently awaiting additional measurements from higher elevations in hopes of identifying the maximum LGM ice thickness. Our new 14C results, in combination with longer-lived nuclides and geomorphic evidence will start to paint a more complete picture of the Antarctic ice sheet.