Siderophile element characteristics of acapulcoite–lodranites and winonaites: Implications for the early differentiation processes of their parent bodies

Yoshihiro HIDAKA1,4, Naoki SHIRAI1, Akira YAMAGUCHI2,3, and Mitsuru EBIHARA1,4
Meteoritics & Planetary Science (in Press) Link to Article []
1Department of Chemistry, Tokyo Metropolitan University, Tokyo 192-0397, Japan
2National Institute of Polar Research, Tachikawa, Tokyo 190-8518, Japan
3Department of Polar Science, School of Multidisciplinary Science, SOKENDAI (The Graduate University for AdvancedStudies), Tokyo 190-8518, Japan
4Present address: Department of Earth Sciences, Waseda University, Tokyo 169-8050, Japan
Published by arrangement with John Wiley & Sons

We have studied magnetic fractions of five acapulcoites, three lodranites, and two winonaites to investigate chemical compositions of their precursor materials and metallic partial melting processes occurring on their parent bodies. One winonaite metal is similar in composition to low Au, low Ni IAB iron subgroup, indicating genetic relationship between them. Magnetic fractions of chondrule‐bearing acapulcoite and winonaite have intermediate chemical compositions of metals between H chondrites and EL chondrites. This fact indicates that the precursor materials of acapulcoite–lodranites and winonaites were similar to H and/or EL chondrites in chemical compositions. Magnetic fractions in acapulcoite–lodranites have a large variety of chemical compositions. Most of them show enrichments of W, Re, Ir, Pt, Mo, and Rh, and one of them shows clear depletion in Re and Ir relative to those of chondrule‐bearing acapulcoite. Chemical compositional variations among acapulcoite–lodranite metals cannot be explained by a single Fe‐Ni‐S partial melting event, but a two‐step partial melting model can explain it.


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