Post-LGM evolution of the lower Ord River, WA, constrained by luminescence and cosmogenic radionuclide dating
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Date
2018-12-10
Journal Title
Journal ISSN
Volume Title
Publisher
Australiasian Quaternary Association Inc.
Abstract
The landscape history of northern Australia is significant for understanding both environmental and
human history. In this region the Upper Pleistocene to Holocene represents a period of major flux in
response to external drivers such as climate variation and sea-level change. The influence of these
drivers has been profound, and they have exerted significant controls on landscape form and
composition along Australia’s northern margin. This also has implications for groundwater resources
and quality.
This study investigates the lower Ord River system, a bedrock-dominated catchment in the East
Kimberley region of northwest Western Australia. Geochronological and geomorphological
investigations of landforms of the lower Ord plain, and its paleo-floodplain within the central Ord
River valley, highlight the significance of the terminal stages of the Last Glacial Maximum (LGM) as a
control on regional base level and consequently on landscape change.
The timing of capture of the Ord River from its northeast-draining paleo-valley to its present
westerly course is constrained by cosmogenic radionuclide bedrock exposure ages from Tarrara Bar -
the likely location of capture by westward flowing drainage at ca. 15 ka. Optically-stimulated
luminescence ages from scroll plains on the lower Ord River downstream of Tarrara Bar are younger
than 7 ka, suggesting that their evolution is tied to regional climatic variation affecting sediment
supply to these lower reaches of the system post-LGM sea-level stabilisation.
This landscape history is significant in that it controls the distribution and nature of alluvial materials
within both the current and paleo-valley systems, and has implications for the properties of
depositional units that may influence the distribution and quality of groundwater. © Author(s)
Description
Keywords
Western Australia, Australia, Rivers, Luminescence, Age estimation, Quaternary period, Sea level, Ground water
Citation
Smith, M. L., McPherson, A. A., Cupper, M. L., Fuijoka, T., & Wilcken, K. M. (2018). Post-LGM evolution of the lower Ord River, WA, constrained by luminescence and cosmogenic radionuclide dating. Paper presented at the AQUA Biennial Conference, Canberra, 10-14 December 2018. (pp. 57). https://aqua.org.au/wp-content/uploads/2019/10/AQUA-2018-Program.pdf