SGER Proposal:Pagodroma Group Stratigraphy and Paleontology: Participation in ANARE 2000-2001

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

0091676 Harwood This award, provided by the Office of Polar Programs, allows a US investigator to join a geological field team of the Australian National Antarctic Research Expedition (ANARE) in the Prince Charles Mountains of East Antarctica. The purpose of the fieldwork is to investigate past fluctuations of the East Antarctic Ice Sheet that are recorded in glacial strata of the Pagodroma Group in the region. The mountains flank the sides of the Lambert Graben, through which the largest catchment area of the East Antarctic Ice Sheet drains into Prydz Bay. Preliminary fieldwork on the Pagodroma Group has been conducted by the Russian Antarctic Expeditions and the ANARE. Field and laboratory work has identified several marine fossiliferous in situ stratigraphic units and other units that contain glacially reworked marine sediments >300 km inland from the current coastline. These sediments were deposited during ice sheet and ice shelf retreat, during the Miocene and Pliocene-Pleistocene, and were dated through diatom and foraminiferal biostratigraphy and amino acid racemization. Paleoenvironmental conditions during these times of glacial retreat and open marine deposition are determined from in situ marine microfossil data. In contrast, erosional and ice grounding features evident in the strata represent intervals of glacial advance. This award will facilitate collaboration between the principal investigator and Australian colleagues on geological field research during ANARE 2000-2001 and will support subsequent preliminary laboratory analysis on recovered Pagodroma Group materials in order to establish age and paleoenvironmental relationships. Prior field reconnaissance in the area and air photo interpretation of potential new deposits will direct the initial field activities during the coming field season. Chief areas of study are in three regions: the Amery Oasis area, the Lanyon/Meredith area and, if logistical support is available, along the eastern low margin of Fisher Massif. Recent discussions about the Neogene history of Antarctic glaciation center on the age of the Sirius Group and mode of emplacement of marine diatoms in these strata. Preliminary results from coeval strata of the Pagodroma Group support interpretations of significant variation in volume of the East Antarctic Ice Sheet during the Late Neogene. The abundance of diatoms in some intervals of the Pagodroma Group (up to3.5% biogenic silica) and the stratigraphic position of in situ marine diatomaceous laminites prevents contrary discussions about wind-derivation of these marine microfossils. Significant basic documentation of stratigraphy (in the field) and paleontological content (in the laboratory) is required to place the disparate deposits into a temporal and stratigraphic framework and enable correlation within the Prince Charles Mountains and into other areas of Antarctica. If preliminary examination of the recovered materials identifies productive samples for micropaleontological analysis, a follow-up proposal will be prepared to support further study of these materials.