Deciphering Petrogenetic Histories of Polymict Regolith Breccias from the Moon, Mars, and 4 Vesta

• Author / Creator

  Saini, Radhika

• The geological histories of planetary bodies in our solar system can be understood by unraveling the petrogenetic histories and evolution of regolith breccias derived from their planetary surfaces. This study investigates three meteoritic breccias, Northwest Africa (NWA) 14340, Sariçiçek, and NWA 10922, originating from the Moon, 4 Vesta, and Mars, respectively. The breccias’ formation processes and evolutions are unraveled through comprehensive petrological analyses, coupled with literature synthesis. This study reveals distinct stages in the petrogenetic histories of the breccias, with impact cratering processes playing an important role at each stage:
  
  Stage 1: Clast excavation and regolith mixing, showcasing the dominance of impact cratering and gardening processes across the Moon, 4 Vesta, and Mars.
  Stage 2: Lithification processes, which varied among the breccias: NWA 14340 possibly underwent shock or temperature-induced processes; Sariçiçek was shock-lithified; and NWA 10922 underwent thermal annealing, recrystallizing its matrix around clasts. The location of each breccia’s lithification relative to the locus of impact cratering emerged as a critical factor influencing lithification under different pressure or temperature regimes.
  Stage 3: Post-lithification processes, NWA 14340 and Sariçiçek exhibit no evidence of post-lithification modification, such as thermal metamorphism or hydrothermal activity. In contrast, NWA 10922 shows evidence of secondary mineral formation due to hydrothermal activity (Lorand et al. 2015), suggesting a dynamic geological history with near-surface water involvement.
  Stage 4: Excavation processes reflect the varying escape velocities and regolith turnover rates of the respective planetary bodies. NWA 14340 experienced shock pressures near the Moon’s surface high enough to melt the matrix and quench to glass with a high-pressure mineral assemblage of tissintite, coesite  garnet. In contrast, low shock pressures were sufficient for the excavation of lithified Sariçiçek and NWA 10922 from 4 Vesta and Mars, respectively.
  Implications of this study offer insights into the geological evolution of the Moon, 4 Vesta, and Mars. The variations in lithification processes, from shock-induced compaction to thermal annealing, highlight the diverse processes operating on these planetary bodies. These findings contribute to our broader understanding of planetary geology and provide valuable constraints for future studies aiming to unravel the complex histories of rocky planetary bodies in our solar system.

• Subjects / Keywords

  • regolith breccia
  • shock metamorphism
  • Mars
  • Moon
  • 4 Vesta
  • petrogenesis
  • formation
  • evolution
  • breccia

• Graduation date

  Fall 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-g4a1-5893

• License

  This thesis is made available by the University of Alberta Library 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.