Meteorites on the Nullarbor Plain, insights from synchrotron powder diffraction

Introduction: The Australian deserts are an excellent place to search for meteorites, the dry warm climate limits changes on the surface allowing meteorites to remain in place for hundreds, if not thousands of years. Additionally, the Nullarbor plain – one of the largest limestone karst systems in the world provides an additional benefit in colour, the light limestone contrasting the black meteorites well. Over the past decade a group from Monash have been searching for these meteorites and with moderate success have collected over 200 new meteorites. This represents approximately 1/5 of Australia’s meteorite collection. Although the Nullarbor provides a fairly stable environment, there are still variations in the weathering of these meteorites and it is important to establish if this is just a result of time on the surface or if there is also a location and local environment factors. While these meteorites have been studied using optical and SEM techniques, synchrotron XRD (SXRD), represents a fast way to gain detailed bulk mineralogy of these samples to complement and add to the existing data. It can also be combined with geo-spatial data associated with the samples to model and determine weathering patterns for the meteorites on the Nullarbor. To this end we plan to study a wide selection of Australian Meteorites of various classes using SXRD to determine the phases present, with particular sensitivity to minor phases, both original and weathered mineral phases. Fig. 1. Context image to show meteorite collection sites. The meteorites described here are a mixture of officially described meteorites and new, as yet, unclassified meteorites from the Nullarbor as well as having a range of compositions. The samples were chosen as being a large enough sample, or multiple fragments, so that a representative sample (~0.5g) could be crushed while leaving enough for other analyses. Figure 1 shows the collection area for these meteorites. The meteorites which are not officially classified have been named for the date they were found (DDMMYY) and then alphabetically for the order they were found that day.

Keywords

Meteorites, South Australia, Synchrotrons, X-ray diffraction, Deserts, Arid lands

Citation

Brand, H. E. A., Langendam, A. D., Whitworth, A. J., Alkemade, S. L., Mitchell, J. T., Davis, A., Stephen, N. R. & Tomkins, A. G. (2019). Meteorites on the Nullarbor Plain, insights from synchrotron powder diffraction. Poster presented at the 50th Lunar and Planetary Science Conference, The Woodlands, Texas, USA, 18 to 22 March 2019 (No. 2132, pp. 1361). Retrieved from: https://www.hou.usra.edu/meetings/lpsc2019/authorindex.cfm

URI

https://www.hou.usra.edu/meetings/lpsc2019/authorindex.cfm
https://apo.ansto.gov.au/dspace/handle/10238/12017

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