Browsing by Author "Cupper, ML"

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    Cemented in time: formation of the 20 000 year old Willandra fossil trackway
    (Geological Society of Australia, 2014-07-07) Graham, IT; Whiteside, E; Ward, C; Cendón, DI; Westaway, M; Cupper, ML; Woodhead, JD
    The Willandra Lakes system of southwestern NSW is situated within the Murray Basin, and consists of 19 interconnected relict lake basins. In general, the lake sediments within the Willandra Lakes system consist of wellsorted quartz sands (with typical lacustrine shelly fauna), associated with deeper water clays and sandy clays. In 2003, the region was found to host the largest known in-situ tract of Pleistocene human footprints in the world, with the site located on the shoreline of a small, relict lake basin between Lakes Garnpung and Leaghur. Optically Stimulated Luminescence dating revealed that the sediments were deposited between 19 000 and 20 000 years ago. The area is of great cultural value to the local Aboriginal communities (the traditional tribal groups Paakantyi, Mutthi Mutthi and Ngiyampaa), as well as to both the national and international scientific communities. Detailed mineralogical (quantitative XRD), geochemical (XRF, ICP-MS, stable isotopes) and textural (petrography, SEM) analyses of the sediments were undertaken to help determine their origin and provide a basis for their future conservation. The footprints themselves are impressed into a hardpan unit, surrounded by low sand dunes. Approximately 820 m2 of the hardpan has been excavated and explored. The footprint-bearing sediments are composed of a series of thin laminae totalling 150 mm thick, accumulated over repeated cycles of wetting and drying. These sediments are largely composed of pelloids and intraclasts of authigenic clay-sized particles (<2–8 μm) of ferroan magnesite (or hydromagnesite/palygorskite), eolian-derived fractured quartz grains and minor (<10 wt%) kaolinite/illite. There is a large lateral and vertical variation in the modal mineralogy; the NE corner contains 90.5 wt% ferroan magnesite (and minor smithsonite) while the SW and W parts contain 49 wt% ferroan magnesite. The other sediments are largely composed of eolian quartz (up to 85 wt%), kaolinite, illite, rutile, albite, microcline, hematite, goethite and rare dolomite. In terms of stable isotopes, the ferroan magnesite carbonate has a δ13C of –2.5‰ while the hydromagnesite has δ13C of 0.4‰. The magnesite, hydromagnesite and palygorskite appear to have been derived through precipitation within the lake. Although direct precipitation of these phases is rare under surficial conditions, it can occur if there is a high Mg/Ca, only possible if extensive early precipitation of calcite cements occurred before the waters entered into the lake. As the lake dried-out, there was an increase in salinity resulting in a decrease in the activity of water in solution, thereby increasing the hydrated Mg2+ leading to magnesite precipitation.
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    Late quaternary fire regimes of Australasia
    (Elsevier, 2011-01) Mooney, SD; Harrison, SP; Bartlein, PJ; Daniau, AL; Stevenson, J; Brownlie, KC; Buckman, S; Cupper, ML; Luly, J; Black, M; Colhoun, EA; D’Costa, D; Dodson, JR; Haberle, SG; Hope, GS; Kershaw, P; Kenyon, C; McKenzie, M; Williams, N
    We have compiled 223 sedimentary charcoal records from Australasia in order to examine the temporal and spatial variability of fire regimes during the Late Quaternary. While some of these records cover more than a full glacial cycle, here we focus on the last 70,000 years when the number of individual records in the compilation allows more robust conclusions. On orbital time scales, fire in Australasia predominantly reflects climate, with colder periods characterized by less and warmer intervals by more biomass burning. The composite record for the region also shows considerable millennial-scale variability during the last glacial interval (73.5–14.7 ka). Within the limits of the dating uncertainties of individual records, the variability shown by the composite charcoal record is more similar to the form, number and timing of Dansgaard–Oeschger cycles as observed in Greenland ice cores than to the variability expressed in the Antarctic ice-core record. The composite charcoal record suggests increased biomass burning in the Australasian region during Greenland Interstadials and reduced burning during Greenland Stadials. Millennial-scale variability is characteristic of the composite record of the sub-tropical high pressure belt during the past 21 ka, but the tropics show a somewhat simpler pattern of variability with major peaks in biomass burning around 15 ka and 8 ka. There is no distinct change in fire regime corresponding to the arrival of humans in Australia at 50 ± 10 ka and no correlation between archaeological evidence of increased human activity during the past 40 ka and the history of biomass burning. However, changes in biomass burning in the last 200 years may have been exacerbated or influenced by humans. © 2011, Elsevier Ltd.
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    Post-LGM evolution of the lower Ord River, WA, constrained by luminescence and cosmogenic radionuclide dating
    (Australiasian Quaternary Association Inc., 2018-12-10) Smith, ML; McPherson, AA; Cupper, ML; Fuijoka, T; Wilcken, KM
    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)
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    Skeletal arsenic of the pre-Columbian population of Caleta Vitor, northern Chile
    (Elsevier B.V., 2015-06-01) Swift, J; Cupper, ML; Greig, A; Westaway, MC; Carter, C; Santoro, CM; Wood, R; Jacobsen, GE; Bertuch, F
    Exposure to toxic arsenic has severe health consequences for past and present societies. This research resolves changes in a pre-Industrial population's exposure to the toxin within an arsenic-endemic area of the Atacama Desert of northern Chile over long timescales. Inductively coupled plasma mass spectrometry (ICP-MS) trace element analysis of human bone and tooth samples from 21 burials at Caleta Vitor on the Pacific coast of northern Chile has established that the pre-Columbian inhabitants were exposed to elevated levels of arsenic where one third of the sample population had accumulated levels in their skeletal system indicative of chronic poisoning. Coupled with new accelerator mass spectrometry (AMS) radiocarbon ages for the skeletal samples, spanning c. 3867 to 474 cal BP and encompassing all major cultural periods of the region, these results demonstrate the continual risk of arsenic poisoning over several millennia of occupation at one site. Numerous factors may have partially contributed to the population's inferred poisoning, due to the complex interaction of various environmental sources of arsenic and human behaviours. Increased exposure to arsenic could relate to climatic variability influencing sources of drinking water or anthropogenic activities such as mining and metallurgy or dietary changes associated with agriculture. Assessment of these potential sources of arsenic toxication, including evaluation of modern environmental data from the region, suggests contaminated drinking water was the most likely cause of arseniasis. © 2015 Elsevier Ltd.