Cemented in time: formation of the 20 000 year old Willandra fossil trackway

Simple item page
dc.contributor.authorGraham, ITen_AU
dc.contributor.authorWhiteside, Een_AU
dc.contributor.authorWard, Cen_AU
dc.contributor.authorCendón, DIen_AU
dc.contributor.authorWestaway, Men_AU
dc.contributor.authorCupper, MLen_AU
dc.contributor.authorWoodhead, JDen_AU
dc.date.accessioned2017-02-14T23:22:39Zen_AU
dc.date.available2017-02-14T23:22:39Zen_AU
dc.date.issued2014-07-07en_AU
dc.date.statistics2017-02-15en_AU
dc.description.abstractThe 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.en_AU
dc.identifier.citationGraham, I., Whiteside, E., Ward, C., Cendón, D. I., Westaway, M., Cupper, M., & Woodhead, J. (2014). Cemented in time: formation of the 20 000 year old Willandra fossil trackway. Presentation to the Australian Earth Sciences Convention 2014 (AESC 2014), 22nd Geological Convention, Newcastle NSW, 7-10 July 2014, (pp. 220-221). Retrieved from: http://aesc2014.gsa.org.au/assets/Various-reg-partner-opp-workshop-summ-/AESC-Abstract-Proceedings.pdfen_AU
dc.identifier.conferenceenddate10 July 2014en_AU
dc.identifier.conferencenameAustralian Earth Sciences Convention 2014, Newcastle NSW, AESC 2014. 22nd Geological Conventionen_AU
dc.identifier.conferenceplaceNewcastle, New South Walesen_AU
dc.identifier.conferencestartdate7 July 2014en_AU
dc.identifier.govdoc7868en_AU
dc.identifier.issn0729 011 Xen_AU
dc.identifier.pagination220-221en_AU
dc.identifier.urihttp://aesc2014.gsa.org.au/assets/Various-reg-partner-opp-workshop-summ-/AESC-Abstract-Proceedings.pdfen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/8304en_AU
dc.language.isoenen_AU
dc.publisherGeological Society of Australiaen_AU
dc.subjectLakesen_AU
dc.subjectSedimentsen_AU
dc.subjectIsotopesen_AU
dc.subjectQuartzen_AU
dc.subjectClaysen_AU
dc.subjectPleistocene epochen_AU
dc.titleCemented in time: formation of the 20 000 year old Willandra fossil trackwayen_AU
dc.typeConference Abstracten_AU
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
AESC-Abstract-Proceedings.pdf
Size:
4.46 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Conference Publications