^1,2Amanda Ostwald,¹Arya Udry,³James M. D. Day,^4,5,6,7Juliane Gross
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14159]
¹Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
²Smithsonian National Museum of Natural History, Washington, DC, USA
³Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
⁴NASA Johnson Space Center, Houston, Texas, USA
⁵Department of Earth and Planetary Science, Rutgers University, Piscataway, New Jersey, USA
⁶Lunar and Planetary Institute, Houston, Texas, USA
⁷Department of Earth and Planetary Sciences, The American Museum of Natural History, New York, New York, USA
Published by arrangement with John Wiley & Sons

Nakhlite and chassignite meteorites are cumulate rocks thought to originate from the same location on Mars. Petrogenetic relationships between nakhlites and chassignites are not fully constrained, and the two cumulus phases in nakhlites—olivine and clinopyroxene—possibly formed either together from one magma or separately from different magmas. Primary magma compositions can potentially be determined from studies of melt inclusions (MIs) trapped within early-formed mineral phases. MIs frequently undergo post-entrapment effects, and when such processes occur, there can be significant changes to their compositions. Here, we report major, minor, and trace element abundances for MIs in cumulus phases in nakhlites and chassignites. The melt compositions that they record are variable (MgO = 2.50–13.5 wt%, K2O = 0.03–3.03 wt%, La/Yb = 2.46%–16.4%) and are likely affected by diffusive reequilibration with changing magma composition outside of their host phases. Evidence for diffusive reequilibration suggests that nakhlite and chassignite magmas were generated in an open system, and cumulus phases may have undergone magma storage and mixing. Such processes may be akin to those that occur in terrestrial intrusive magmatic systems by open-system magma recharge. MIs within the nakhlite and chassignite suite therefore provide insights into magmatic processes during magma storage and transit on Mars.