High-pressure minerals in eucrite suggest a small source crater on Vesta

Area of Science:

• Planetary Science
• Mineralogy
• Geochemistry

Background:

• High-pressure minerals in meteorites are key indicators of shock events on planetary bodies.
• Impact craters are common on Vesta, but high-pressure minerals are rare in Howardite-Eucrite-Diogenite (HED) meteorites.

Purpose of the Study:

• To identify and characterize high-pressure minerals in the NWA 8003 eucrite.
• To determine the pressure and temperature conditions of shock events recorded in the meteorite.

Main Methods:

• Microscopic and chemical analysis of minerals in the NWA 8003 meteorite.
• Comparison of mineral compositions with shock event simulations.

Main Results:

• First evidence of tissintite, vacancy-rich clinopyroxene, and super-silicic garnet found in NWA 8003.
• Melt vein solidification occurred between >~10 GPa and <~8.5 GPa at temperatures exceeding 1900°C.
• Simulations indicate ~3 km diameter impact craters could generate these pressures.

Conclusions:

• The presence of these minerals suggests shock events on Vesta were more common than previously assumed.
• HED meteorites with similar high-pressure mineral assemblages may be more prevalent than current discoveries indicate.