Age and uplift rates of Sirius Group sediments in the Dominion Range, Antarctica, from surface exposure dating and geomorphology [An article from: Global and Planetary Change]

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Description:
The recent tectonic history of the Dominion Range is a key component in the debate over the age and significance of the Sirius Group glacial sediments. Outcrops at Oliver Bluffs along the Beardmore Glacier contain fossil wood (Nothofagus), mollusks, fish and insects that have been biostratigraphically dated by close association with late Pliocene (4 Myr) exposure prior to deposition of the Nothofagus bearing units. This scenario is incompatible with the observed stratigraphy and climatic conditions necessary to support Nothofagus, and indicates these key Sirius group sediments are much older than 3.8 Ma. The conspicuous faults and grabens in the Dominion Range are interpreted as sackungen features attributed to gravitational failure resulting from oversteepening of the range flanks by glacial erosion by the Beardmore and Mill outlet glaciers rather than the result of tectonic uplift.