Unraveling the Components within Apollo 16 Ferroan Anorthosite Suite Cataclastic Anorthosite Sample 60025: Implications for the Lunar Magma Ocean Model

1M. A. Torcivia,1C. R. Neal
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2020JE006799]
1University of Notre Dame
Published by arrangement with John Wiley & Sons

The ferroan anorthosite suite (FAS) represents the only direct sampling of the lunar magma ocean (LMO) and potentially contains information on the earliest history of the Moon. Apollo 16 FAS sample 60025 is extremely important for understanding early lunar evolution, but unraveling this information is complicated. For example, 60025 has two distinct Sm-Nd crystallization ages that in themselves encapsulate the complicated history of this sample, along with the cataclastic and heterogeneous textures exhibited. Here we present new in-situ major and trace element plagioclase and pyroxene data gathered from 5 thin sections of 60025 that highlight such complexities. Trace element data are used to derive equilibrium liquids and while many of the minerals analyzed here are consistent with derivation from the LMO, there are also a significant number of plagioclase and pyroxene crystals that crystallized from magmas inconsistent with current models of LMO evolution. Integration of Sm-Nd isotopic data with the elemental data reported here indicated a non-chondritic LMO is possible and we confirm that 60025 is a polymict lunar breccia containing differently sourced material.


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