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|Title:||The brine zone in the McMurdo Ice Shelf, Antarctica|
|Authors:||National Science Foundation (U.S.). Division of Polar Programs.|
Gow, Anthony Jack.
Cragin, James H.
Morey, Rexford M.
Radio echo sounding
|Publisher:||Cold Regions Research and Engineering Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||CRREL report ; 82-39.|
Abstract: Observations of a 4.4-m-high brine step in the McMurdo Ice Shelf. Antarctica, show that it has migrated about 1.2 km in 4 years. The present brine wave is overriding an older brine-soaked layer. This migration is proof of the dynamic nature of the step, which is the leading edge of a brine wave that originated at the shelf edge after a major break-out of the McMurdo Ice Shelf. The inland boundary of brine penetration is characterized by a series of descending steps that are believed to represent terminal positions of separate intrusions of brine of similar origin. The inland boundary of brine percolation is probably controlled largely by the depth at whlch brine encounter, the firn/ice transition (43 m). However, this boundary is not fixed by permeability considerations alone, sinoe measurable movement of brine is still occurring at the inland boundary. Freeze-fractionation of the seawater as it migrates through the ice shelf preferentially precipitates virtually all sodium sulfate, and concomitant removal of water by freezing in the pore spaces of the infiltrated firn produces residual brines approximately six times more concentrated than the original seawater.
|Appears in Collections:||CRREL Report|