T43 Impact Cratering: Geologic, Geochemical, and Geophysical Signatures on the Terrestrial Planets (Posters)

Sunday, 4 November 2018
9:00 AM - 5:30 PM
Halls J-K

SHOCK FEATURES IN MINERAL GRAINS FROM PSEUDOTACHYLITE BRECCIA OF THE MUSGRAVE PROVINCE AUSTRALIA

Paper number: T43-12
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Abstract

Early researchers interpreted the pseudotachylite breccia from the Musgrave Province Australia as generated by normal seismic processes despite the large volume of the deposits. The Musgrave pseudotachylite breccias deposits are about 5km wide and run intermittently for 300km with approximately 4% to 10% pseudotachylite melt. The seismic origin was postulated based on the proximity of the Woodroffe Thrust Fault, with up to three generations of pseudotachylite melts found in some of the Musgrave samples. This traditional seismic interpretation continued even though some pseudotachylite deposits are radial to an impact center (MAPCIS) and 40km from the Woodroofe Thrust Fault along with multiple generation pseudotachylite being known to occur at other large impact sites.

The evidence on the mega and macro scale along elemental analysis with having been found and presented over the last ten years in support of a large impact in central Australia coeval with the established dating of the Precambrian/Cambrian boundary, the ultimate evidence is the finding of shock features within the minerals, specifically the pseudotachylite breccia, near the impact center.

Petrographic investigation revealed shocked quartz grain with multiple sets of PDFs, along with shocked feldspar and diaplectic glasses the wall rock adjacent to the pseudotachylite melt.

The results strongly suggest Musgrave province pseudotachylite breccia received shock forces consistent with a large impact.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-323970

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