Cryogenic origin for brine in the subsurface of southern McMurdo Sound, Antarctica

Sampling of interstitial fl uids during deep coring in southern McMurdo Sound, Antarctica, revealed the presence of seawater-sourced, hypersaline brine at depths >200 m below the seafl oor. Na-Cl-Br and SO4-Cl-Br relationships are consistent with a concentration mechanism that involves the remova...

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Bibliographic Details
Published in:Geology
Main Authors: Frank, T. D., Gui, Z., ANDRILL SMS Science Team tra cui, Cornamusini, G.
Other Authors: ANDRILL SMS Science Team tra, Cui
Format: Article in Journal/Newspaper
Language:English
Published: 2010
Subjects:
Antarc*
Antarctica
Ice Sheet
McMurdo Sound
Ross Sea
Sea ice
Online Access:http://hdl.handle.net/11365/998225
https://doi.org/10.1130/G30849.1
Description
Summary:Sampling of interstitial fl uids during deep coring in southern McMurdo Sound, Antarctica, revealed the presence of seawater-sourced, hypersaline brine at depths >200 m below the seafl oor. Na-Cl-Br and SO4-Cl-Br relationships are consistent with a concentration mechanism that involves the removal of pure H2O as ice and precipitation of mirabilite (Na2SO4ยท10H2O) during progressive freezing of seawater. The brine is in Neogene subglacial, glacimarine, and marine facies that record advance and retreat of glaciers through the Ross Sea embayment. In this environment, sea ice formation in semi-isolated marine basins that occupied fl exural troughs along ice sheet margins produced dense brines that sank and infi ltrated the permeable subglacial sediment. Repeated cycles of glacial advance and retreat provided multiple opportunities for batches of seawater to be transformed into brine that now is in the subsurface of southern McMurdo Sound. Results demonstrate the feasibility of brine formation via seawater freezing and attest to the potential of a cryogenic origin for subsurface brines in high-latitude regions of the Northern Hemisphere, as proposed by some workers.

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