GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 179-14
Presentation Time: 9:00 AM-6:30 PM


CONNELLY, Daniel P.1, SIKDER, Arif M.2, BRUM, Jose3, HILL, Tina R.4 and LIU, Xin-Cheng2, (1)MAPCIS Research Project, 4815 Covered Bridge Rd, Millville, NJ 08332, (2)Virginia Commonwealth University (VCU), Center for Environmental Studies (CES), Richmond, VA 23284, (3)Olympus Scientific Solutions Americas, 48 Woerd Ave, Suite 105, Waltham, MA 02452, (4)Bruker AXS Inc., 5465 E. Cheryl Parkway, Madison, WI 53711,

In 2011, pseudotachylite breccias from the Musgrave Province, Northern Territory, Australia were studied from locations 40km, 60km and 100km from a proposed impact site, known as MAPCIS, where 2kg to 5kg samples that contain pseudotachylite breccia were collected. The samples were initially sliced in Coober Pedy and Adelaide, Australia and were later verified as pseudotachylite breccia in 2012 by both Actlabs Ltd., Canada and Applied Petrographic Services Inc., USA. This pseudotachylite breccia was put into context of an impact and compared the geomorphology to pseudotachylite breccia of the Vredefort structure, South Africa at the: 34th IGC Brisbane 2012, GSA Annual Meeting in Charlotte 2012 , 35h IGC Cape Town 2016 and the 2016 GSA Annual Meeting in Denver.

In 2017, a new line of investigation was opened as there is an Iridium anomaly associated with the Precambrian/Cambrian boundary. For the first time, this pseudotachylite breccia from the Musgrave province was assayed for Iridium as well as other PGEs. The samples from the Musgrave province along with samples of Pt. from the Sudbury Canada and Vredefort, SA impact sites were prepared at Virginia Commonwealth University to be assayed at Bureau Veritas Commodities Canada Ltd. The results showed an Iridium anomaly in the Musgrave pseudotachylite orders of magnitude higher than what would be expected from continental crust. The Iridium enrichment in the samples is consistent with an extraterrestrial source or possibly a mantle source. Further sampling and assaying may be needed to fully differentiate the source of the Iridium enrichment.

Although pseudotachylite breccias in central Australia are the largest known deposits on Earth, they are relatively unknown and unstudied. Samples were donated to the Australian Museum, Sydney, the South Australian Museum, Adelaide, the Queensland Museum, Brisbane and Naturhistorisches Museum, Vienna. These samples were the first of their kind in each museum collection. We hope to stimulate further research in this area.

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