Mincy mesosiderite metallic nodules analyzed by EBSD: an approach to understanding their thermal history.

GARCIA, LAURA NOEL; MARIA EUGENIA VARELA; HWANG S.L.; SHEN, POUYAN; BOLAMARO, RAUL; AVALOS, MARTINA

Meteoritics and Planetary science

WIley

Lugar: New York; Año: 2022 vol. 57 p. 1958 - 1972

1945-5100

Meteorites carry information about the most common processes that have beenactive in the early solar system. In particular, mesosiderites are meteorites with a structureconsidered to be composed of equal parts of iron–nickel metal and silicates. A naturaldelimitation in the study of such complex systems is the discrimination of the iron–nickelmetallic and silicate domains. In this work, we focus on the metallic phases of the Mincymesosiderite, a specimen available at the ICATE repository. In Mincy, the metallic phasesare iron–nickel–carbon alloys that are distributed forming metallic lumps or pebbles(referred to as metallic nodules in the manuscript) in which kamacite and taenite arepresent, and taenite is found both at the kamacite/silicate interface and surrounded bykamacite, that is, isolated from the silicates. We made use of the EBSD technique todetermine the crystallographic orientation relationships along the taenite/kamaciteboundaries as well as for characterizing the (hkl)-specific grain boundaries regarding theunderlying tilt, twist, or twinning mechanism to assist the interpretation of the phasetransformations and mechanisms that could explain the formation of these metallic nodules.From the results, each of the metallic nodules has a unique temperature–pressure historyand kinetics to undergo phase transformations (mainly partial melting, heterogeneousnucleation-controlled solidification, and possible evaporation–condensation) as well asliquid-phase sintering and recrystallization in its own way.