Integrated Provenance Characteristics of East Antarctic Glacial Sediments
Abstract
The composition of glacial sediments from Antarctica helps to elucidate its largely hidden geology and also provides an important framework for evaluating iceberg contributions to the ocean over time. We are applying a suite of sediment provenance tracing techniques to glacial-marine diamict samples from East Antarctica. This study is a nearshore complement to a circum-Antarctic survey of the Nd isotope compositions of < 63- micron terrigenous sediments and the Ar/Ar ages of individual hornblendes separated from offshore core top sediments by Roy et al., (Chemical Geology, submitted). Roy et al. observed that Nd model ages and single- step laser fusion Ar/Ar analyses of individual hornblende grains captured the main features of the East Antarctic, West Antarctic, and Antarctic Peninsula geologic terranes, and the tectonic evolution of Antarctica including a major thermal resetting event at approximately 500 Ma. The most diverse sector of the survey area was Wilkes Land, with large peaks in the age spectrum at 1500-1800 Ma and 1100-1300 Ma, smaller peaks at ~~400-600 Ma and 0-200 Ma. This study exams ice proximal samples from the Wilkes Land Margin between 143 E and 63 E longitude, from the George V Coast to Prydz Bay. Samples were collected from jumbo piston cores taken in inner continental shelf basins, fjords, and bays during cruise NBP01-01. Diamict represents sampling and homogenization over large areas, avoiding possible biasing in limited and heterogeneous outcrops, while also avoiding the competing influences of sediment redistribution by ocean currents. These proximal samples will allow characterization of potential iceberg sources. This study will provide an integrated characterization of the lithic clast composition, bulk sediment geochemistry, iron oxide mineralogy and geochemistry, Ar/Ar ages of hornblende grains, and radiogenic isotope signatures and will thus allow fingerprinting sediment supplied to the Southern Ocean by the East Antarctic Ice Sheet.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMPP23A1731B
- Keywords:
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- 0726 Ice sheets;
- 1040 Radiogenic isotope geochemistry;
- 1050 Marine geochemistry (4835;
- 4845;
- 4850);
- 1065 Major and trace element geochemistry;
- 4926 Glacial