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G070: Collaborative Research: Dating and paleoenvironmental studies on ancient ice in the Dry Valleys, Antarctica

Start date:
Late October
End date:
mid January
Locations:
Beacon Valley, Up Wright Valley
Principle Investigator:
Michael Bender
Organisation:
Princeton University
State
New Jersey
Field season overview:
Field team members will establish three separate field camps in Beacon and Mullins Valleys. They will use pre-existing campsite locations and pre-existing helicopter pads wherever possible. Throughout the field season, they will assist G-440 with sample collection and geomorphological interpretation, and may initiate one or two personnel exchanges between groups. Researchers plan to drill and collect ice cores (each as much as 20-30 m deep) at five localities along the debris-covered glacier to determine the age of the ice by dating trapped gases held within. This will help reconstruct aspects of atmospheric greenhouse gas concentrations and regional climate in the past. Ice cores will be periodically retrograded to McMurdo Station and will be returned to CONUS at the end of the season.
The Mullins Valley debris-covered glacier forms at the headwall of Mullins Valley, Dry Valleys region of Antarctica. As it flows down this small valley, it enters a region of net ablation, and mass loss leads to the surface exposure of dirt and rocks that fell in at the headwall. The dirt/rock layer, which eventually reaches a thickness of about 1 m, insulates the ice and causes evaporation to be very slow. In addition, glacial flow alleviates thinning due to ablation, so that glacial ice is foreshortened laterally, rather than vertically. The consequence of these two features is that very old ice is preserved: 40Ar/39Ar ages of volcanic ashes found in the rock layer progressively increase down the length of the glacier, and reach nearly 10 Ma at the outer limit.