Permafrost distribution and active‐layer depths in the McMurdo Dry Valleys, Antarctica

Abstract

The McMurdo Dry Valleys (MDVs) constitute the largest ice‐free area (6700 km2) in Antarctica. Permafrost is ubiquitous in the region and is present as ground ice or buried ice, ice‐cemented permafrost and dry‐frozen permafrost. Using a combined dataset that includes more than 800 shallow (<1.5 m) excavations, we provide a map at a scale of 1:2 million showing the distribution of permafrost in the MDVs. Our data suggest that about 55% of the permafrost is ice cemented, 43% is dry frozen and ground/buried ice comprises at least 2% of the area. Permafrost form is related to climatic zone, age of sediments and local site factors. Ice is present in ice‐cored alpine moraines and coastal tills of Holocene age in hummocky drifts of late Quaternary age (ca. <115 ka); however, it is also present in Miocene‐aged sublimation till in Beacon Valley. Ice‐cemented permafrost is present not only in coastal areas (subxerous climatic zone) and in sediments of late Quaternary age, but also in soils of pre‐Quaternary‐age in ultraxerous regions along the polar plateau. Dry‐frozen permafrost exists along the floors and lower sidewalls of larger ice‐free valleys (xerous climatic zone) in sediments of pre‐late Quaternary age. Dry‐frozen permafrost, which may be unique to Antarctica, appears to form from sublimation of moisture in ice‐cemented permafrost over time. Active‐layer depths are 45 to 70 cm in coastal areas and in the eastern half of Wright and Taylor Valleys, 20 to 45 cm in other ice‐free areas within 60 km of McMurdo Sound, and <20 cm along the polar plateau. Copyright © 2007 John Wiley & Sons, Ltd.

Thermal state of permafrost and active‐layer monitoring in the antarctic: Advances during the international polar year 2007–2009

“…This region has been intensively studied for several decades by a number of researchers and a permafrost monitoring program was implemented in the late 1990s (see e.g. Campbell and Claridge, 2006;Guglielmin, 2006;Bockheim et al, 2007;Bockheim and McLeod, 2008;Gordon and Balks, 2008;Adlam et al, 2010). Given the low temperatures recorded during the IPY (Figure 6), permafrost in the Transantarctic Mountains is not as likely to thaw in the near future as the warm permafrost in the Antarctic Peninsula region.…”

New constraints on equatorial temperatures during a Late Neoproterozoic snowball Earth glaciation

“…(11). The presence of sand wedges rather than ice wedges, as well as the aeolian sand sheet, suggests an arid paleoenvironment where ground ice concentrations, guided by modern observations (Berg and Black, 1966;Bockheim et al, 2007;Campbell et al, 1998), may have been only a few percent.…”

Local influences of geothermal anomalies on permafrost distribution in an active volcanic island (Deception Island, Antarctica)

“…Permafrost, which occupies only 0.36% (49,800 km 2 ) of the Antarctic region, is present beneath virtually all ice-free terrain, except at the lowest elevations of the maritime Antarctic and sub-Antarctic islands (Ramos et al, 2012). Permafrost occurrence has been confirmed in the South Shetlands by many authors (Ramos et al, 1989;Serrano and López-Martinez, 2000;Hall, 2002;Bockheim et al, 2007;Vieira et al, 2010, among others), who also noted several permafrost-free sites at low altitude. Due to a tectonic setting of Bransfield strait opening (rift aperture), some of these sites show a high geothermal heat flux, such as Bridgeman, Penguin and Deception islands (De Rosa et al, 1995;Gràcia et al, 1996), inhibiting the development of large thickness of permafrost.…”