Xie, Z. D., Sharp, T., & DeCarli, P. (2008). The mineralogy of shock-induced melt vein in Martian meteorite Zagami: Shock pressure and ejection mechanism. Bulletin of Mineralogy Petrology and Geochemistry, 27(4), 351-355.
Abstract
The observations by transmission electron microscopy showed that the 125 μm wide shock-induced melt vein in Martian meteorite Zagami consisting of abundant long-shaped stishovite needles plus minor troilite droplets and pyroxenes in the background of silicate glass. This is the first report of Post-stishovite was found in zagami meteorite in the maskelynite outside of shock-induced melt vein. The mineralogy assemblages of melt vein, including stishovite, pyroxene and other high-pressure phases reported by others, indicated the melt-vein crystallization pressure and shock pressure were smaller than 25 GPa. The occurrence of post-stishovite indicated post-stishovite is a production of a solid-state transformation. The Martian meteorite apparently were ejected from Mars during hypervelocity impact event, accelerated to great than the Martian escape velocity (5 km/s) to escape from Martian gravity, and captured by Earth later. The 5 km/s velocity requires a shock pressure of at least 65 GPa in high-pressure ejection mechanism which is inconsistent with Martian meteorite have been subjected to the pressure of less than 25 GPa in general. Although […]
Keywords
- Crystallization pressure
- Ejection
- Martian meteorite
- Melt vein
- Shock
- Shock pressure
- Zagami
