Constraining the Source Craters of the Martian Meteorites: Shock Analysis and Geologic Mapping of Candidate Craters

• Author / Creator

  Hamilton, Jarret

• The ~143 martian meteorites serve as the only rock samples from Mars that are presently available for study in a laboratory setting. These predominantly igneous samples are sourced from the near-surface units adjacent to craters formed during random, hypervelocity impacts of asteroids on the martian surface. Shergottites, a subset of martian meteorites with variable compositions that are otherwise analogous to terrestrial basalts, have crystallization ages that range from 150-2400 Ma and cosmic ray exposure ages that indicate they were ejected from Mars in impact events that occurred <20 Ma ago. Analysis of shock metamorphism in a suite of 13 previously unstudied martian meteorites was conducted. A combination of optical microscopy, scanning electron microscopy, and laser micro-Raman spectroscopy was used to constrain peak shock pressures and identify high-pressure minerals. Two distinct groups of meteorites based on shock deformation and transformation in the bulk rock were observed, and a detailed shock history was inferred from mineral assemblages, high-pressure phases, and morphology of the shock melt. Potential martian meteorite source craters were identified using a database of 290 well-preserved craters on the martian surface. Querying based on attributes from four shergottites further limited the number of potential source craters. These attributes include a range of permissible source crater diameters as constrained by impact modeling, craters occurring on Amazonian-age (~3.37 Ga - Present) volcanic terrains, and the model and relative ages of the craters and their nearby surfaces. Results yielded 52 potential source craters for at least one of four shergottites (Zagami, Tissint, Chassigny, NWA 8159); of these potential source craters, the 8 most well-preserved craters that are potential sources for any of the four meteorites were chosen for further analysis and mapping. These 8 candidate craters and their surrounding geological features were mapped in detail using a combination of visible (CTX, HiRISE, HRSC) and thermal inertia (THEMIS) imagery. Mapping results combined with previous research on crater ages and surface ages were used to evaluate and rank the likelihood of the 8 craters as source(s) of martian meteorites. I find that Zunil, Corinto, and Tooting are the most probable sources of at least one of the shergottites.

• Subjects / Keywords

  • mars
  • martian
  • meteorites
  • shock
  • geologic
  • mapping
  • source
  • craters

• Graduation date

  Spring 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-7hzx-sn70

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.