Pliocene Paleoenvironment and Antarctic Ice Sheet Behavior: Evidence From Wright Valley

Investigations in Wright Valley, adjacent to the Transantarctic Mountains in East Antarctica, shed light on the question of whether high‐latitude Pliocene climate was warm enough to cause widespread deglaciation of the East Antarctic craton with a concurrent Magellanic moorland‐like environment. If...

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Bibliographic Details
Published in:The Journal of geology 1997-05, Vol.105 (3), p.285-294
Main Authors: Hall, Brenda L., Denton, George H., Lux, Daniel R., Schlüchter, Christian
Format: Article
Language:English
Subjects:
Alpine glaciers
Antarctic regions
Basalt
Climate
Geology
Glacial landforms
Gravel
Ice
Ice sheets
Mesas
Moraines
Paleoclimatology
Valleys
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Summary:Investigations in Wright Valley, adjacent to the Transantarctic Mountains in East Antarctica, shed light on the question of whether high‐latitude Pliocene climate was warm enough to cause widespread deglaciation of the East Antarctic craton with a concurrent Magellanic moorland‐like environment. If Pliocene‐age diatoms, presently in glaciogenic deposits high in the Transantarctic Mountains, had come from seaways on the East Antarctic craton, an expanding Late Pliocene ice sheet must have first eroded them from marine sediments and then deposited the diatoms at their present high‐altitude locations. This hypothetical expanding glacier would have had to have come through Wright Valley. Glacial drift sediments from the central Wright Valley were mapped, sampled, analyzed, and40Ar/39Ar whole‐rock dated. Our evidence indicates that an East Antarctic outlet glacier has not expanded through Wright Valley, and hence cannot have overridden the Dry Valleys sector of the Transantarctic Mountains, any time in the past 3.8 myr. Rather, there was only moderate Pliocene expansion of local cold‐based alpine glaciers and continuous cold‐desert conditions in Wright Valley. Persistence of a cold‐desert paleoenvironment implies that the sector of the East Antarctic Ice Sheet adjacent to Wright Valley has remained relatively stable without melting ablation zones since at least 3.8 Ma, in Early Pliocene time. A further implication is that Antarctic Ice Sheet behavior in the Pliocene was much like that in the Quaternary, when the ice sheet consisted of a stable, terrestrial core in East Antarctica and a dynamic, marine‐based appendage in West Antarctica.
ISSN:0022-1376
1537-5269
DOI:10.1086/515922