Petrography, mineral chemistry and shock metamorphism of Yamato 984028 lherzolitic shergottite

Y984028 is a new lherzolitic shergottite, consisting of poikilitic and non-poikilitic lithologies. The mafic silicates are FeO-poor, and the chromite is TiO2-poor in the poikilitic lithology compared to the grains in the non-poikilitic lithology. This meteorite shares similar mineral petrography and mineral chemistry with GRV 99027, but is not paired with the latter because of their different shock-induced features. Y984028 was severely shocked and experienced no significant thermal metamorphism after the main impact event. Hence, Y984028 serves as a probe for the study of meteorite impact processes on terrestrial surfaces. The melt veins in Y984028 are characterized by the absence of any high-pressure polymorphs, the presence of abundant small mineral fragments, and the prevailing granulation textures of olivine and chromite. These features are consistent with adiabatic melting during the release of shock-induced high-pressure and quenching at ambient pressure.