Record Search Query:[Parameters: Topic='SOLID EARTH', Term='ROCKS/MINERALS', Variable_Level_1='AGE DETERMINATIONS']
Determining the geochronology of the Taylor Valley from the study of the geomorphology, lake levels, sediments and climatic events during the past 400,000 years
Abstract:
Fieldwork was carried out in the Taylor Valley over several seasons to determine the geochronology of the area.The lake beds and the geomorphology of a series of hummocks between the Suess and LaCroix Glaciers, were investigated for a carbonate rich sediment that was discovered here in a previous visit. Isotopic analysis suggested that the carbonates had been deposited from water of polar glacial ... composition, but attempted 14C dating showed they were beyond the limit of carbon dating. Samples were collected to try dating by the U-Th technique. The deposit was exposed for about 100m along the north bank of the stream draining west from the Suess Glacier. The geomorphology of sediments between the Suess and LaCroix Glaciers was studied by investigating a complex series of kame-like mounds, with a relief of 10-15m on the floor of the Taylor Valley, collecting samples of in situ carbonate with careful elevation control and site description and dating the samples with the U-Th technique. The longitudinal profile and elevations of well preserved deltas were measured on two streams draining into Lake Fryxell. Carbonate was sampled from several in situ locations and subjected to geochemical analysis.The geochronology of the Taylor Valley was investigated from dating samples from sediments recovered from Lake Bonney, aragonite lake beds exposed to the East of Lake Bonney and occurring as part of the desert lag both to the west and the east of Lake Bonney. Numerous samples were collected from around Lake Chad, the Canada Glacier and Lake Fryxell. In situ carbonate right on the well marked 900ft strandline that runs the entire length of the Tyalor Valley from New Harbour to beyond the Rhone Glacier was sampled and subjected to both 14C and U-Th dating. Several carbonate samples relating to advances of the Canada Glacier in the Lake Hoare area were also sampled and dated. Samples of carbonate were collected from the northeastern shoreline of Mt Discovery and Cape Royds to correlate the Quaternary events with those recognised in the Taylor Valley.
Quality
Data contained within the logistics report of the event submitted to Antarctica New Zealand, the following can be found:
Table 3: Summary of Antarctic U/Th dates (Sample number and location, U ppm, U234/U238, Age x 10-3, comments) - contact AntNZ for details. Figure 4: Startigraphic column of soil carbonate, Lake Henderson, Taylor Valley. Interpretations from the geochemistry and dating of the deposits allow several events to be identified: a) 185,000-210,000 years BP and 95,000- 125,000 years BP. These are described in a paragraph. For more information, please contact the investigator.
