Unique achondrite Northwest Africa 11042: Exploring the melting and breakup of the L Chondrite parent body

Zoltan Vaci; Carl B. Agee; Munir Humayun; Karen Ziegler; Yemane Asmerom; Victor Polyak; Henner Busemann; Daniela Krietsch; Matthew Heizler; Matthew E. Sanborn; Qing-Zhu Yin

arXiv · 2102.01281

Unique achondrite Northwest Africa 11042: Exploring the melting and breakup of the L Chondrite parent body

Zoltan Vaci·Carl B. Agee·Munir Humayun·Karen Ziegler·Yemane Asmerom·Victor Polyak·Henner Busemann·Daniela Krietsch·Matthew Heizler·Matthew E. Sanborn·Qing-Zhu Yin

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Abstract

Northwest Africa (NWA) 11042 is a heavily shocked achondrite with medium-grained cumulate textures. Its olivine and pyroxene compositions, oxygen isotopic composition, and chromium isotopic composition are consistent with L chondrites. Sm-Nd dating of its primary phases shows a crystallization age of 4100 +/- 160 Ma. Ar-Ar dating of its shocked mineral maskelynite reveals an age of 484.0 +/- 1.5 Ma. This age coincides roughly with the breakup event of the L chondrite parent body evident in the shock ages of many L chondrites and the terrestrial record of fossil L chondritic chromite. NWA 11042 shows large depletions in siderophile elements (<0.01 times CI) suggestive of a complex igneous history involving extraction of a Fe-Ni-S liquid on the L chondrite parent body. Due to its relatively young crystallization age, the heat source for such an igneous process is most likely impact. Because its mineralogy, petrology, and O isotopes are similar to the ungrouped achondrite NWA 4284 (this work), the two meteorites are likely paired and derived from the same parent body.

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Zoltan Vaci, Carl B. Agee, Munir Humayun, Karen Ziegler, Yemane Asmerom, Victor Polyak, Henner Busemann, Daniela Krietsch, Matthew Heizler, Matthew E. Sanborn, Qing-Zhu Yin. 2021-02-02. Unique achondrite Northwest Africa 11042: Exploring the melting and breakup of the L Chondrite parent body. https://arxiv.org/abs/2102.01281

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