Exploring relationships between shock-induced microstructures and H2O and Cl in apatite grains from eucrite meteorites

The Oxidation State of Sulfur in Apatite of Martian Meteorite—Shergotty

“…Another plausible explanation for the variability in the intensity of the 2,470 eV peak is that the measurement itself is anisotropic, and variations in the apatite crystallographic orientation with respect to the photon beam leads to variability in the intensity of the main K-absorption feature. Because our apatite appears to be in a single grain (though it is fractured, Figures 1 and 2), if our observations of the variable intensity of the 2,470 eV peak are driven by changes in crystallographic orientation, it could suggest that this apatite is deformed, perhaps as the result of shock-induced metamorphism, which has been observed in apatite from other shocked meteorites (Barrett et al, 2021;Černok et al, 2019Darling et al, 2021). As mentioned earlier, Shergotty has experienced one shock event, causing post-emplacement heating of the meteorite to 200°C-400°C (Duke, 1968;Lambert & Grieve, 1984;Stöffler et al, 1986) at shock pressures ∼30.5 GPa and is described as moderately shocked (Fritz et al, 2017).…”

Nanostructural domains in martian apatites that record primary subsolidus exsolution of halogens: Insights into nakhlite petrogenesis

“…DOI: https://doi.org/10.2138/am-2022-8794. http://www.minsocam.org/ al., 2019; Barrett et al, 2021;Darling et al, 2021). However, given that the nakhlites are the least shocked martian meteorites (~15-20 GPa; e.g., Malavergne et al, 2001;Treiman and Irving, 2008), the effects of shock on apatite and other minerals are considered minimal, and apatite in the nakhlites represent a good starting point to observe structures related to their petrogenetic formation processes.…”