¹Peiyu Wu,¹Kyle Dayton,¹Esteban Gazel,²Teresa Porri
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14180]
¹Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York, USA
²Cornell Institute of Biotechnology, Cornell University, Ithaca, New York, USA
Published by arrangement with John WIley & Sons

Estimation of the composition of planetary rocks and minerals is crucial for understanding their formation processes. In this study, we present the application of X-ray nano-computed tomography (nano-XCT) for non-destructive three-dimensional (3-D) phase analysis and estimation of phase abundances in rare Martian meteorite samples, specifically chassignite Northwest Africa (NWA) 2737. We determined the most suitable laser power for minimizing artifacts and maximizing phase contrast. By utilizing nano-XCT, we successfully identified and segmented primary phases in the bulk meteorite sample. Additionally, we were able to locate and segment crystallized silicate melt inclusions within the meteorite. The phase abundances in bulk NWA 2737 and within melt inclusions calculated using nano-XCT were in good agreement with previous studies that used thin section calculations, demonstrating the reliability of nano-XCT as a non-destructive alternative for estimating bulk phase abundances in rare samples. This study develops a benchmarking protocol and demonstrates the efficacy of nano-XCT as a non-destructive technique for generating an overview of phase distribution and assemblages of melt inclusions within rare samples. Future research can benefit from combining non-destructive 3-D phase assemblage estimations with non-destructive 3-D chemical analysis techniques to achieve a fully non-destructive parental magma composition estimation of rare cumulate samples.

¹Tom Boonants,¹Steven Goderis,¹Bastien Soens,¹Flore Van Maldeghem,^2,3Stepan M. Chernonozhkin,²Frank Vanhaecke,⁴Matthias van Ginneken,¹Christophe Snoeck,¹Philippe Claeys
Meteoritics & Planetary Science (in Press)  Link to Article [https://doi.org/10.1111/maps.14188]
¹Archaeology, Environmental Changes and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
²Department of Chemistry, Atomic & Mass Spectrometry A&MS Research Unit, Ghent University, Ghent, Belgium
³Chair of General and Analytical Chemistry, Montanuniversität Leoben, Leoben, Austria
⁴Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury, UK
Published by arrangement with John Wiley & Sons

Upon passage through Earth’s atmosphere, micrometeorites undergo variable degrees of melting and evaporation. Among the various textural and chemical groups recognized among cosmic spherules, that is, melted micrometeorites, a subset of particles may indicate anomalously high degrees of vaporization based on their chemical and isotopic properties. Here, a selection of such refractory element-enriched cosmic spherules from Widerøefjellet (Sør Rondane Mountains, East Antarctica) is characterized for their petrographic features, major and trace element concentrations (N = 35), and oxygen isotopic compositions (N = 23). Following chemical classification, the highly vaporized particles can be assigned to either the “CAT-like” or the “High Ca-Al” cosmic spherule groups. However, through the combination of major and trace element concentrations and oxygen isotopic data, a larger diversity of processes and precursor materials are identified that lead to the final compositions of refractory element-enriched particles. These include fragmentation, disproportional sampling of specific mineral constituents, differential melting, metal bead extraction, redox shifts, and evaporation. Based on specific element concentrations (e.g., Sc, Zr, Eu, Tm) and ratios (e.g., Fe/Mg, CaO + Al2O3/Sc + Y + Zr + Hf), and variations of O isotope compositions, “CAT-like” and “High Ca-Al” cosmic spherules likely represent a continuum between mineral endmembers from both primitive and differentiated parent bodies that experienced variable degrees of evaporation.