Late Eocene Glaciofluvial to Glaciomarine transition in the Lambert Graben: Constraints from lithofacies and mineralogy of ODP Site 1166 sediments, Prydz Bay, Antarctica
K. Strand, J. Köykkä, J. Lamminen, 2013. "Late Eocene Glaciofluvial to Glaciomarine transition in the Lambert Graben: Constraints from lithofacies and mineralogy of ODP Site 1166 sediments, Prydz Bay, Antarctica", Antarctic Palaeoenvironments and Earth-Surface Processes, M. J. Hambrey, P. F. Barker, P. J. Barrett, V. Bowman, B. Davies, J. L. Smellie, M. Tranter
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The transition from a glaciofluvial to a glacial sedimentary environment contains critical information for evaluating the onset of glaciation and early glacial dynamics in Antarctica. This study presents investigations of a sediment core from Ocean Drilling Program Leg 188, Site 1166, on the continental shelf in Prydz Bay, in order to provide evidence for the first occurrence of late Eocene glaciers in the Lambert Graben, East Antarctica. The Lambert Graben is a large fault-bounded structure, at least 700 km long and 100 km wide, and presently hosts the Lambert Glacier–Amery Ice Shelf system. The core consists of middle Eocene glacially influenced alluvial plain sediments, c. 110 m in total thickness that are overlain by a c. 20 m-thick early Oligocene glaciomarine succession. The upper contact is a major unconformity. Grain-surface microtextures, such as fractured plates and a relatively high content of ilmenite in alluvial outwash-plain sediments, indicate mixed northern and southern Prince Charles Mountains provenance and initiation of glaciers as early as middle Eocene time. Distribution of the major heavy minerals indicates a change to garnet-rich granulite terrain in sediment-supply during later ice-sheet evolution, when a lack of detritus from the southern Prince Charles Mountains becomes apparent. Glacier advance was no longer restricted to the Lambert Graben and the drainage area became wider. Good preservation of these low-stand glaciofluvial outwash-plain deposits was related to regional subsidence that progressed to a marine transgression and glaciomarine deposition when ice was able to advance to the continental shelf edge.
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Antarctic Palaeoenvironments and Earth-Surface Processes
The volume highlights developments in our understanding of the palaeogeographical, palaeobiological, palaeoclimatic and cryospheric evolution of Antarctica. It focuses on the sedimentary record from the Devonian to the Quaternary Period. It features tectonic evolution and stratigraphy, as well as processes taking place adjacent to, beneath and beyond the ice-sheet margin, including the continental shelf.
The contributions in this volume include several invited review papers, as well as original research papers arising from the International Symposium on Antarctic Earth Sciences in Edinburgh, in July 2011. These papers demonstrate a remarkable diversity of Earth science interests in the Antarctic. Following international trends, there is particular emphasis on the Cenozoic Era, reflecting the increasing emphasis on the documentation and understanding of the past record of ice-sheet fluctuations. Furthermore, Antarctic Earth history is providing us with important information about potential future trends, as the impact of global warming is increasingly felt on the continent and its ocean.