Rock-forming minerals of paralava in Mongolian Combustion Metamorphic Complexes

[Marco E. Ciriotti]

Referenza:
▪ Glushkova, V.E., Peretyazhko, I.S., Savina, E.A., Khromova, E.A. (2023): Major Rock-Forming Minerals of Paralava in Mongolian Combustion Metamorphic Complexes. Zapiski RMO, 152(4), 65-83.

Abstract:
The characteristics of the composition of rock-forming minerals (plagioclases, clinopyroxenes, melilites) of paralavas of pyrometamorphic complexes of Mongolia, which were formed in the process of high-temperature transformations of carbonate-terrigenous rocks of sedimentary strata during multi-stage natural coal fires, are given. Melilite-nepheline paralavas contain phenocrysts of ferruginous ackermanite-aluminoakermanite, diopside-hedenbergite, containing up to 49 mol. % end of kushiroite CaAlAlSiO 6, and basic plagioclase. Enstatite-ferrosilite is a rock-forming mineral of plagioclase–pyroxene ± indialite paralavas. Paralavas often contain xenoliths of thermally altered sedimentary rocks. Mineral associations in relics of marly limestone xenoliths, composed of gehlenite, monticellite-kirsteinite, perovskite, Al-enriched clinopyroxene, spinel and other minerals, were formed at the stage of high-temperature metamorphism of the sedimentary protolith, preceding the melting of carbonate-silicate rocks, and as a result of the reaction interaction of xenoliths with pyrogenic silicate rocks. melts of different compositions.