The Fukang pallasite: Characterization and implications for the history of the Main‐group parent body

1Daniella N. DellaGiustina,1Namrah Habib,1Kenneth J. Domanik,1Dolores H. Hill,4Dante S. Lauretta,2Yulia S. Goreva,3Marvin Killgore,4Yang Hexiong,4Robert T. Downs
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13313]
1Lunar and Planetary Laboratory, 1629 E University Blvd Tucson, Arizona, 85721 USA
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 91109 USA
3Southwest Meteorite Laboratory, PO Box 95, Payson, Arizona, 85547 USA
4Department of Geosciences, University of Arizona, 1040 4th St, Tucson, Arizona, 85721 USA
Published by arrangement with John Wiley & Sons

We report the results of a study of the Fukang pallasite that includes measurements of bulk composition, mineral chemistry, mineral structure, and petrology. Fukang is a Main‐group pallasite that consists of semiangular olivine grains (Fo 86.3) embedded in an Fe‐Ni matrix with 9–10 wt% Ni and low‐Ir (45 ppb). Olivine grains sometimes occur in large clusters up to 11 cm across. The Fe‐Ni phase is primarily kamacite with accessory taenite and plessite. Minor phases include schreibersite, chromite, merrillite, troilite, and low‐Ca pyroxene. We describe a variety of silicate inclusions enclosed in olivine that contain phases rarely or not previously reported in Main‐group pallasites, including clinopyroxene (augite), tridymite, K‐rich felsic glass, and an unknown Ca‐Cr silicate. Pressure constraints determined from tridymite (<0.4 GPa), two‐pyroxene barometry (0.39 ± 0.07 GPa), and geophysical calculations that assume pallasite formation at the core–mantle boundary (CMB), provide an upper estimate on the size of the Main‐group parent body from which Fukang originated. We conclude that Fukang originated at the CMB of a large differentiated planetesimal 400–680 km in radius.

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