Pleistocene cyclostratigraphy on the continental rise and abyssal plain of the western Ross Sea, Antarctica

• Main Author: Olga Al'bot
• Format: Thesis
• Language: unknown
• Published: 2016
• Subjects: Marine Geoscience; Sedimentology; Pleistocene; Cyclostratigraphy; Ross Sea; Antarctica; School: School of Geography; Environment and Earth Sciences; Unit: Antarctic Research Centre; 040310 Sedimentology; 040305 Marine Geoscience; 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts); Degree Discipline: Geology; Degree Level: Masters; Degree Name: Master of Science; Antarctic; Antarc*; Ice Sheet; Ice Shelf; Sea ice
• Online Access: https://doi.org/10.26686/wgtn.17061797.v1; https://figshare.com/articles/thesis/Pleistocene_cyclostratigraphy_on_the_continental_rise_and_abyssal_plain_of_the_western_Ross_Sea_Antarctica/17061797

This thesis investigates glacimarine sedimentation processes operating on the continental margin of the western Ross Sea during the Pleistocene (˜2.5 Ma). This time period is characterised by a major global cooling step at ˜0.8 Ma, although several proposed episodes of major marine-based Antarctic Ice Sheet (AIS) retreat in warm interglacial periods are inferred to have occurred after this time. Constraining the timing and magnitude of past marine-based AIS retreat events in the Ross Sea through this time will improve our understanding of the forcing mechanisms and thresholds that drive marine-based ice sheet retreat. Identifying such mechanisms and thresholds is crucial for assisting predictive models of potential ice sheet collapse in a future world with rapidly rising atmospheric carbon dioxide (CO₂) concentrations. Six sedimentary cores forming a north-to-south transect from the continental rise to the abyssal plain of the western Ross Sea were examined in order to identify potential sedimentary signatures of past marine-based ice sheet variability and associated oceanographic change. A lithofacies scheme and stratigraphic framework were developed, which allowed the identification of shifting sedimentary processes through time. The sediments are interpreted to have been deposited primarily under the influence of bottom currents, most likely from changing rates of dense Antarctic Bottom Water (AABW) formation over glacial-interglacial cycles. Two dominant lithofacies (laminated and bioturbated) are recognised in the Pleistocene contourite sequences. Laminated facies alongside reduced ice-rafted debris (IRD) fluxes and reduced biological productivity are interpreted to represent expanded ice sheet and sea ice margins during glacial conditions, which acted to restrict surface water ventilation resulting in less oxygenated bottom waters. Conversely, laminated facies alongside reduced IRD fluxes and increased productivity are inferred to represent a reduction of ice shelf and sea ice cover resulting in enhanced ...