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Age‐Depth Stratigraphy of Pine Island Glacier Inferred From Airborne Radar and Ice‐Core Chronology
Author(s) -
Bodart J. A.,
Bingham R. G.,
Ashmore D. W.,
Karlsson N. B.,
Hein A. S.,
Vaughan D. G.
Publication year - 2021
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1029/2020jf005927
Subject(s) - geology , chronology , ice core , glacier , ice sheet , ice stream , physical geography , antarctic ice sheet , glacial period , climatology , oceanography , δ18o , cryosphere , paleontology , sea ice , stable isotope ratio , geography , physics , quantum mechanics
Abstract Understanding the contribution of the West Antarctic Ice Sheet (WAIS) to past and future sea level has been a major scientific priority over the last three decades. In recent years, observed thinning and ice‐flow acceleration of the marine‐based Pine Island Glacier has highlighted that understanding dynamic changes is critical to predicting the long‐term stability of the WAIS. However, relatively little is known about the evolution of the catchment during the Holocene. Internal reflecting horizons (IRHs) provide a cumulative record of accumulation, basal melt, and ice dynamics that, if dated, can be used to constrain ice‐flow models. Here, we use airborne radars to trace four spatially extensive IRHs deposited in the late Quaternary across the Pine Island Glacier catchment. We use the WAIS Divide ice‐core chronology to assign ages to three IRHs: 4.72 ± 0.28, 6.94 ± 0.31, and 16.50 ± 0.79 ka. We use a 1‐D model, constrained by observational and modeled accumulation rates, to produce an independent validation of our ice‐core‐derived ages and provide an age estimate for our shallowest IRH (2.31–2.92 ka). We find that our upper three IRHs correspond to three large peaks in sulfate concentrations in the WAIS Divide ice‐core record and hypothesize that the origin of these spatially extensive IRHs is from past volcanic activity. The clear correspondence between our IRHs and the ones previously identified over the Weddell Sea Sector, altogether representing ∼20% of the WAIS, indicates that a unique set of stratigraphic markers spanning the Holocene exists over a large part of West Antarctica.