Article

Meteorite stranding surfaces and the Greenland icesheet

Authors:
  • Maine Mineral and Gem Museum
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Abstract

Abstract— Thirty years of recoveries in East Antarctica have led to significant understanding of the regional characteristics associated with meteorite stranding surfaces. In Antarctica these sites are characterized by patches of snow-free blue ice at high altitude on the icesheet in regions where iceflow is highly restricted. Melting is extremely rare or absent and sublimation rates are high, even though meteorite stranding surfaces are predominantly found within regions where accumulation typically dominates. Localized environmental conditions that persist for thousands of years or longer appear to be the dominant factor rather than shorter-term or seasonal cycles. In this paper we describe our discovery of regions in Northeast Greenland with blue ice areas that exhibit many of the requisite characteristics, suggesting that they are excellent prospects for future meteorite recovery efforts.

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... However, seemingly identical ice fields can have very different meteorite concentrations, and many of the ice fields that have been found in Antarctica have shown few or no meteorites at all. Some factors have been identified that may be used as proxies to evaluate the potential of a given blue ice field (Harvey et al. 2001). High-elevation areas with low precipitation, limited or preferentially no summer melting, strong katabatic winds, and stagnant ice flow seem to have the best potential for building up meteorite concentrations. ...
... High mountains block the ice flow toward the coast, creating areas of stagnant ice at high elevations. Blue ice is seen at elevations of up to 2600 m in Kong Christian X Land and up to 2000 m in Dronning Louise Land (Harvey et al. 2001). Although Kong Christian X Land is at 2 degrees lower latitude than Dronning Louise Land, we found the former more promising since the higher elevation suggests a mean average temperature about 3 °C lower (Reeh 1989). ...
Article
Abstract— Following discoveries of blue ice areas in Greenland resembling meteorite-bearing blue ice fields in Antarctica, a surface search of several of the most promising sites was carried out in August 2003. The ice fields are located in Kong Christian X Land, in northeastern Greenland around 74°N at elevations between 2100 and 2400 m. No meteorites were found in any of the localities that were searched. Evidence of occasional significant melting (filled crevasses and melt sheets) suggest that summer temperatures are sometimes high enough that dark rocks, like meteorites, can melt through the upper layers of ice. Small terrestrial rocks and cryogenite were found down to 50 cm below the ice surface. Meter-sized terrestrial rocks were found on top of the ice downstream from nunataks. These rocks shade the ice below, and since they were apparently too massive to warm up during warm days, they remained at the surface as the surrounding ice ablated away. Our findings strongly suggest that Greenland is currently unlikely to harbor significant meteorite concentrations on blue ice fields.
... In addition, in the Queen Fabiola Mountains, the BIA outlines have been manually adjusted to include all the blue ice from one of Antarctica's prime meteorite collection locations: the Yamato BIA. BIAs with an average altitude below 200 m (calculated using the surface elevation data) (33) are not considered because meteorite concentrations there are highly unlikely (they are typically found above 1500 m, due to the adverse climatic conditions at lower elevation) (49). ...
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