Evaluating the Duration and Continuity of Potential Climate Records From the Allan Hills Blue Ice Area, East Antarctica

Abstract

The current ice core record extends back 800,000 years. Geologic and glaciological evidence suggests that the Allan Hills Blue Ice Area, East Antarctica, may preserve a continuous record that extends further back in time. In this study, we use ice-penetrating radar and existing age constraints to map the internal stratigraphy and age structure of the Allan Hills Main Ice Field. The dated isochrones provide constraints for an ice flow model to estimate the age of ice near the bed. Previous drilling in the region recovered stratigraphically disturbed sections of ice up to 2.7 million years old. Our study identifies a sitẽ 5 km upstream, which likely preserves a continuous record through Marine Isotope Stage 11 with the possibility that the record extends back 1 million years. Such records would provide new insight into the past climate and glacial history of the Ross Sea Sector.

The spatial flux of Earth’s meteorite falls found via Antarctic data

“…(neglecting the effect of wind, which removes lighter and smaller fragments much more quickly; Benoit and Sears, 1999;Folco et al, 2002). It is crucial to note that this surface residency time scale does not necessarily equate with a meteorite's terrestrial age (i.e., the duration of time since that meteorite arrived on Earth), which is likely to be far greater for englacial samples (Kehrl et al, 2018).…”

Unravelling the high-altitude Nansen blue ice field meteorite trap (East Antarctica) and implications for regional palaeo-conditions

“…Furthermore, blue ice areas have the potential to contain surface or shallow ice that is older than that recovered from deep drilling projects and can in some cases provide a higher temporal resolution (e.g. Sinisalo et al, 2007;Higgins et al, 2015;Bibby et al, 2016;Kehrl et al, 2018). Equally important, ice is available in large quantities, which is necessary for certain types of measurements, such as the characterization of trapped gasses and their isotopic composition (e.g.…”

Enhanced Moisture Delivery into Victoria Land, East Antarctica During the Early Last Interglacial: Implications for West Antarctic Ice Sheet Stability

“…Finally, regardless the cause(s) of the LIG spike in S27 accumulation rate, it has significant glaciological implications in terms of ice flow modeling for the Allan Hills BIA, where ice older than 2 million years (Ma) has been discovered in sites disconnected from the main ice flow line (Yan et al, 2019). Recent ice-penetrating radar surveys and ice flow modeling by Kehrl et al (2018) have suggested the potential preservation of a stratigraphically continuous ice record, with 1 Ma ice located 25 to 35 m above the bedrock. The modeling efforts by Kehrl et al (2018) assume no-higher-than-present accumulation rates in the past and constant sublimation rates that control the exhumation of ice along the flow line.…”

“…Recent ice-penetrating radar surveys and ice flow modeling by Kehrl et al (2018) have suggested the potential preservation of a stratigraphically continuous ice record, with 1 Ma ice located 25 to 35 m above the bedrock. The modeling efforts by Kehrl et al (2018) assume no-higher-than-present accumulation rates in the past and constant sublimation rates that control the exhumation of ice along the flow line. In light of the discovery of this work, models with the time-dependent accumulation rate constrained by observations could better predict the age-depth profile.…”

“…The accumulation area of the ice feeding the Allan Hills BIA today lies about 20 km upstream (Kehrl et al, 2018). An accumulation rate of 0.0075 m yr -1 for the past ~660 years is inferred from a shallow firn core drilled near the Allan Hills BIA (Dadic et al, 2015).…”