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

1,2Laura Noel García,1María Eugenia Varela,3Shyh-Lung Hwang,4Pouyan Shen,5Raúl Bolmaro,5Martina Ávalos
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13911]
1Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (ICATE), Universidad Nacional de San Juan, CONICET, J5402DSP San Juan, Argentina
2Instituto de Mecánica Aplicada, Universidad Nacional de San Juan, J5400ARL San Juan, Argentina
3Department of Materials Science and Engineering, National Dong Hwa University, 974 Hualien, Taiwan, ROC
4Department of Materials and Optoelectronic Science, National Sun Yat-sen University, 804 Kaohsiung, Taiwan, ROC
5Instituto de Física Rosario (IFIR), Universidad Nacional de Rosario, CONICET, S2000EKF Rosario, Argentina
Published by arrangement with John Wiley & Sons

Meteorites carry information about the most common processes that have been active in the early solar system. In particular, mesosiderites are meteorites with a structure considered to be composed of equal parts of iron–nickel metal and silicates. A natural delimitation in the study of such complex systems is the discrimination of the iron–nickel metallic and silicate domains. In this work, we focus on the metallic phases of the Mincy mesosiderite, a specimen available at the Instituto de Ciencias Astronómicas, de la Tierray y del Espacio repository. In Mincy, the metallic phases are iron–nickel–carbon alloys that are distributed forming metallic lumps or pebbles (referred to as metallic nodules in the article) in which kamacite and taenite are present, and taenite is found both at the kamacite/silicate interface and surrounded by kamacite, that is, isolated from the silicates. We made use of the electron backscattered diffraction technique to determine the crystallographic orientation relationships along the taenite/kamacite boundaries as well as for characterizing the (hkl)-specific grain boundaries regarding the underlying tilt, twist, or twinning mechanism to assist the interpretation of the phase transformations and mechanisms that could explain the formation of these metallic nodules. From the results, each of the metallic nodules has a unique temperature–pressure history and kinetics to undergo phase transformations (mainly partial melting, heterogeneous nucleation-controlled solidification, and possible evaporation–condensation) as well as liquid-phase sintering and recrystallization in its own way.


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