East Antarctic glacial history through microfossil analyses of the Pagodroma Group

These results provide information on the biostratigraphic age, depositional
environment and paleoclimate setting for four formations of the Pagodroma Group
of glacial deposits. Information includes key biostratigraphic diatom species,
zonal assignments, age relationships and descriptions of strata that
characterize a warmer than present climate regime in Antarctica. The Mt.
Johnston Formation is Oligocene in age, the Fisher Bench Formation is middle or
middle to late Miocene in age, the Battye Glacier Formation is late Miocene in
age, and the Bardin Bluffs Formation is Pliocene in age. Interpretations based
on glacigene strata and fossils of Pagodroma Group of the Prince Charles
Mountains support the persistence of a dynamic, polythermal ice sheet in East
Antarctica until the late Pliocene. Exposures of these glacigene deposits
suggest deposition by an ice sheet of quite different character than the
present ice sheet, and a glacial regime that included significant erosion,
transportation and deposition. In situ marine macrofossils and microfossils
within formations of the Pagodroma Group indicate that this warmer than present
climate regime, and polythermal character of the East Antarctic ice sheet
continued through the late Miocene and into the Pliocene. The floating ice
margin retreated up the Lambert Valley by as much as 300 km south of its
present grounded limit, where distal glacimarine facies deposited diatomaceous
muds of the Battye Glacier (late Miocene) and Bardin Bluffs (Pliocene)
formations. The grounding zone of the paleo-Lambert Glacier/Amery Ice Shelf
system fluctuated across a distance greater than 600 km during the Neogene,
from a position on the continental shelf edge in Prydz Bay to the inner reaches
of the Lambert/Amery Embayment. Further information can be found in the
following published references (see Reference Section at the bottom of the
page).