On the occurrences and formation mechanisms of cliftonites: the case of Campo del Cielo iron meteorite

GARCIA, LAURA NOEL; SHEN P; QUIRICO E.; VARELA M.E.; MONTAGNAC G.; TOLLEY, ALFREDO; STEFABESCU D.; BARUJ A,

CARBON

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2023

0008-6223

he origin and shock history of IAB meteorites are still a matter of debate. From the literature,the study of carbon phases can provide further information on the thermal conditions to whichthe meteorites have been exposed. Within this framework, the occurrences of cliftonites –classically defined as graphite aggregates– in a sample of the Campo del Cielo iron meteorite,were explored through optical and electron microscopy, and Raman spectroscopy. Theassessment of carbon organization within the cliftonites, allowed us to propose a partial meltingprocess of the kamacitic matrix followed by its resolidification and the optimization of the shapeorientation relationships by the host crystal. This scenario combined with the cliftonitescharacterization at the micro and nanoscale led us to suggest a growth mechanism for thecliftonites in our Campo del Cielo sample, while the results from previous studies could accountfor cliftonites formation under diverse temperature-pressure-composition conditions as it isexpected among different specimens and within them.