Abstract
AbstractThe englacial stratigraphic architecture of internal reflection horizons (IRHs) as imaged by ice‐penetrating radar (IPR) across ice sheets reflects the cumulative effects of surface mass balance, basal melt, and ice flow. IRHs, considered isochrones, have typically been traced in interior, slow‐flowing regions. Here, we identify three distinctive IRHs spanning the Institute and Möller catchments that cover 50% of West Antarctica's Weddell Sea Sector and are characterized by a complex system of ice stream tributaries. We place age constraints on IRHs through their intersections with previous geophysical surveys tied to Byrd Ice Core and by age‐depth modeling. We further show where the oldest ice likely exists within the region and that Holocene ice‐dynamic changes were limited to the catchment's lower reaches. The traced IRHs from this study have clear potential to nucleate a wider continental‐scale IRH database for validating ice sheet models.
Highlights
Projecting the future of the West Antarctic Ice Sheet (WAIS) and its potential impacts on rising global sea level has developed into a major imperative over recent decades, in response to satellites observing pervasive ice loss (Shepherd et al, 2019) that may indicate the onset (Feldman & Leverman, 2015) of a predicted collapse (Mercer, 1978)
H1 and H2 were traced along several ice‐penetrating radar (IPR) lines linking over the ice divide into the Mercer/Kamb Ice Stream catchments and H2 extended into the Pine Island Glacier catchment
Through tracing internal reflection horizons (IRHs) along multiple flightlines over a 210,000 km2 sector of the WAIS dissected by ice stream tributaries, we have demonstrated that tracing englacial IRHs, and englacial surfaces, is possible across the wider continental ice sheet
Summary
Projecting the future of the West Antarctic Ice Sheet (WAIS) and its potential impacts on rising global sea level has developed into a major imperative over recent decades, in response to satellites observing pervasive ice loss (Shepherd et al, 2019) that may indicate the onset (Feldman & Leverman, 2015) of a predicted collapse (Mercer, 1978). In order to have confidence in the ice sheet models used to predict such behavior, they must be informed and calibrated by data‐driven constraints on ice behavior preceding the observational era. To date, such constraints have primarily been provided by paleoclimatic information drawn from surface‐exposure dating, marine sediments and geomorphology, and ice cores (RAISED Consortium, 2014; Steig & Neff, 2018). Few studies have taken advantage of a valuable paleoclimatic resource that exists across much of Antarctica, namely, the internal stratigraphic architecture of the ice itself that has been sounded across much of the continent by ice‐penetrating radar (IPR). Most IPR surveys have sounded numerous englacial internal reflection horizons (IRHs) throughout the ice column (e.g., Steinhage et al, 2001; Winter et al, 2017), and these, away from density‐driven reflectivity contrasts in the near‐surface (Kovacs et al, 1995), and the strained ice of the basal zone where anisotropic effects become important (Fujita et al, 2000; Wang et al, 2018), are widely attributed
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