Graphite-Based Geothermometry on Almahata Sitta Ureilitic Meteorites
Anna Barbaro1, M Chiara Domeneghetti1, Cyrena A Goodrich2
1Department of Earth and Environmental Sciences, University of Pavia, 27100 Pavia, Italy.
Minerals (Basel, Switzerland)
|March 15, 2021
Summary
Ureilite meteorites reveal shock event temperatures through graphite analysis. Micro-Raman spectroscopy indicates these temperatures resulted from impact events, not primary igneous processes.
Area of Science:
- * Planetary Science
- * Geochemistry
- * Mineral Physics
Background:
- * Ureilite meteorites offer insights into early Solar System formation and evolution.
- * The thermal history of carbon phases (graphite, diamond) is crucial for understanding parent body processes.
- * Previous studies suggested impact events formed graphite-diamond assemblages in some ureilites.
Purpose of the Study:
- * To determine the thermal history of graphite in Almahata Sitta (AhS) ureilite meteorites.
- * To investigate the origin of observed carbon phases and their relation to parent body events.
- * To differentiate between temperatures from igneous processes and shock events.
Main Methods:
- * Micro-Raman spectroscopy was employed for geothermometry on graphite samples.
- * Analysis focused on graphite G-band peak centers and full width at half maximum values.
- * Samples included AhS ureilites: AhS 72, AhS 209b, and AhS A135A.
Main Results:
- * Graphite crystallization temperatures ranged from 1242 °C to 1332 °C.
- * Disordered graphite exhibited a nanometric crystalline domain size (70–140 nm).
- * These characteristics suggest the recorded temperatures are linked to shock events.
Conclusions:
- * The thermal data indicate shock events significantly influenced the ureilite parent body.
- * The nanometric grain size of recrystallized graphite supports a shock origin.
- * Temperatures recorded are likely from impact events, not primary igneous activity.
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