Formation Parameters of High-Pressure Minerals in the Dhofar 717 and 864 Chondrite Meteorites

Resumo

This paper presents the results of a Raman spectroscopic study of shock melt veins in L6 chondritic meteorites Dhofar 717 and 864, and conclusions about the P–T parameters recorded in these meteorites after the impact event. The primary minerals of the host chondrite include olivine, orthopyroxene, clinopyroxene, plagioclase, chromite, phosphates, troilite, and kamasite. Shock melt veins up to 1 cm thick contain fragments of the high-pressure minerals ringwoodite, wadsleyite, majorite, akimotoite, jadeite, lingunite, and tuite and quenched melt consisting of majorite, ringwoodite, troilite, and kamasite. The mineral associations of the Dhofar 717 and 864 chondrites indicate high peak PT parameters of the impact in the region of stability of majorite (>20 GPa and >2500 K) and bridgmanite (>25 GPa and >2500 K). The presence of lingunite also directly indicates a peak pressure in the area of stability of the bridgmanite.