The geochronology and palaeoclimates of relict landscapes on Kangaroo Island.

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dc.contributor.authorWyche, W. J.
dc.contributor.schoolSchool of Physical Sciencesen
dc.date.issued2023
dc.descriptionThis item is only available electronically. Whole thesis (as available).
dc.description.abstractKangaroo Island preserves multiple un-investigated relict landscapes that provide evidence for important changes to effective precipitation in southern Australia during the Late Pleistocene and Holocene (110ka-0ka). These relict landscapes offer a potential means for expanding the sparse Pleistocene southern Australian palaeoclimate record. Three sites that exemplify these long-term changes in hydroclimatology are a lunette at Birchmore Lagoon which formed by deflation of the exposed lake floor during periods of decreased effective precipitation, as well as a fluvial sequence at MacGillivray Sand Quarry and an alluvial floodplain sequence at Willson River, both of which formed during periods of increased effective precipitation and enhanced surface runoff. This thesis aims to provide a synthesised geochronology (single-grain OSL dating), geochemistry (XRF, XRD) and grain size study of these sites to improve understanding of the nature and timing of long-term effective moisture cycles in southern Australia. Six single-grain OSL samples taken at Birchmore Lagoon lunette, two at MacGillivray Sand Quarry and six at Willson River indicate a wide range of depositional ages ranging between 106-0.1 thousand years (ka). Birchmore Lagoon lunette consists of three distinct depositional periods between 106-22 ka, with deposition episodes centred on MIS (marine isotope stage) 5d, MIS 3 and MIS 2, all indicating lake floor exposure and deflation during glacial stages and cooler interglacial sub-stages. Fluvial deposits at MacGillivray Sand Quarry were formed 83-77 ka in MIS 5a, indicating increased effective precipitation and surface runoff around the peak of a warmer interglacial substage. Alluvial floodplain deposits at Willson River accumulated in MIS 1 between 3.2-0.1 ka, revealing periodic increases in effective precipitation during the late Holocene interglacial, potentially coinciding with intensification of ENSO cycle frequency. The results of this study potentially indicate decreased strength or frequency of frontal rainfall from the Southern Ocean during MIS 5d, MIS 3 and MIS 2 as reflected in drier periods at Birchmore Lagoon, as well as increased strength or frequency of frontal rainfall from the Southern Ocean in MIS 5a and MIS 1 as seen in wetter periods at MacGillivray Sand Quarry and Willson River.
dc.description.dissertationThesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, YEAR
dc.identifier.urihttps://hdl.handle.net/2440/146736
dc.language.isoen
dc.provenanceThis electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legalsen
dc.subjectHonours
dc.subjectGeology
dc.subjectKangaroo Island
dc.subjectOSL dating
dc.subjectgeochronology
dc.subjectrelict landscapes
dc.subjectQuaternary
dc.subjectpalaeoclimate
dc.titleThe geochronology and palaeoclimates of relict landscapes on Kangaroo Island.
dc.typeThesis

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