Ahrensite, γ-Fe2SiO4, a new shock-metamorphic mineral from the Tissint meteorite: Implications for the Tissint shock event on Mars

Abstract

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Mineral chemistry of the Tissint meteorite: Indications of two‐stage crystallization in a closed system

“…() and Ma et al. () demonstrated that ringwoodite is actually composed of 0.05–0.4 μm grains. Additionally, the aggregation and preservation of original zoning in ringwoodite suggest that solid‐state transformation is likely the main mechanism for ringwoodite formation in Tissint (Walton et al.…”

“…; Ma et al. ). Such a process is rapid and would occur on a time scale of tens of nano‐seconds (Tschauner et al.…”

Shock-transformation of whitlockite to merrillite and the implications for meteoritic phosphate

“…These localized ‘hotspots' occur at locations of low-shock impedance where a larger fraction of shock energy is converted to heat rather than compression. Sources of hotspot formation include frictional heating between minerals of different impedances, collapse of voids or fluid inclusions or breakdown of hydrous minerals upon shock4246. Whitlockite/merrillite has a lower shock impedance than the major rock-forming minerals in meteorites20.…”

Si-Disordering in MgAl2O4-Spinel under High P-T Conditions, with Implications for Si-Mg Disorder in Mg2SiO4-Ringwoodite

“…In order to confirm their hypothesis, more investigation should be conducted on the meteoritic Rw, which represents the best natural specimen for studying high-P structural features, including the Mg-Si order-disorder state, due to its having much larger quench rates. Rw of various colors has been documented in many meteorites, including L ordinary chondrites [108][109][110][111][112], LL ordinary chondrites [14,26], and Martian meteorites like the shergottites [32,34,37]. If the relationship among the color, composition, inverse magnitude, P and T can be adequately quantified, a fine scale for accurately estimating the shock P-T conditions may be derived, which may serve well the theoretical evolution models of the early solar system.…”