The Tissint Martian meteorite as evidence for the largest impact excavation.
High-pressure minerals in meteorites provide clues for the impact processes that excavated, launched and delivered these samples to Earth. Most Martian meteorites are suggested to have been excavated from 3 to 7 km diameter impact craters. Here we show that the Tissint meteorite, a 2011 meteorite fall, contains virtually all the high-pressure phases (seven minerals and two mineral glasses) that have been reported in isolated occurrences in other Martian meteorites. Particularly, one ringwoodite (75 × 140 μm(2)) represents the largest grain observed in all Martian samples. Collectively, the ubiquitous high-pressure minerals of unusually large sizes in Tissint indicate that shock metamorphism was widely dispersed in this sample (~25 GPa and ~2,000 °C). Using the size and growth kinetics of the ringwoodite grains, we infer an initial impact crater with ~90 km diameter, with a factor of 2 uncertainty. These energetic conditions imply alteration of any possible low-T minerals in Tissint.
Planetary Geosciences Institute, Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA.
Ioannis P
IP
Baziotis
Yang
Y
Liu
Paul S
PS
DeCarli
H Jay
HJ
Melosh
Harry Y
HY
McSween
Robert J
RJ
Bodnar
Lawrence A
LA
Taylor
D003460:Crystallization; D018534:Earth, Planet; D005118:Extraterrestrial Environment; D018535:Mars; D019110:Meteoroids; D008903:Minerals / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D011312:Pressure
D008903:Minerals; D010758:Phosphorus