The stratigraphy of the Pliocene-lower Pleistocene Bardin Bluffs Formation, Amery Oasis, northern Prince Charles Mountains, Antarctica

In the Amery Oasis of the northern Prince Charles Mountains, the glaciomari ne Bardin Bluffs Formation of the Pagodroma Group was deposited between the Late Pliocene (< 3.1 Ma) and Early Pleistocene (>1 Ma). The formation prov ides evidence of (i) a reduced East Antarctic ice sheet compared to that of the present day and (ii) a subsequent Plio-Pleistocene ice sheet expansion . The formation consists of two members. The older, basal Member 1 is c. 12 .5 m thick and consists of relatively ice-distal silty, sandy and sparsely fossiliferous fjordal strata. Member 1 reflects largely ice-free marine sed imentation c. 250 km inland from the current Amery Ice Shelf edge. The memb er is restricted to the area about the north-eastern end of Pagodroma Gorge where it infills a chemically weathered erosion surface, cut in the form o f a valley on the Permo-Triassic Amery Group. Weathering occurred during ae rial exposure of the Amery Oasis in a warmer climate than that of today. Th e younger Member 2 exceeds 40 m in thickness and is made up of coarse ice p roximal glaciomarine diamicts. It overlies disconformably Member 1 at Pagod roma Gorge. Elsewhere, Member 2 rests directly upon a smoothed and striated erosion surface, cut on the Amery Group, which was part of a fjord floor. This erosional surface and the facies contrast between the two members, ind icates an East Antarctic Ice Sheet expansion and Lambert Glacier grounding- line advance.