Petrogenesis of the Amazonian enriched gabbroic shergottite Northwest Africa 13440

As the most common samples available from Mars, shergottites offer important constraints on the igneous history of the planet into the Amazonian epoch. The newly recognized shergottite Northwest Africa (NWA) 13440 is here classified as a gabbroic shergottite and is likely launched‐paired with NWA 6963, exhibiting many of the unusual textural features of that sample. The Sm‐Nd isotope systematics of NWA 13440 yielded an errorchron age of 206 ± 34, with an εNd i = −7.1. This age and εNd i , coupled with a bulk rock (La/Yb) N of 1.02, allow for its classification as an enriched shergottite. The presence of unusual augite inclusions in pigeonite laths testifies to the importance of undercooling and nonequilibrium crystallization early in the history of the parental magma of the meteorite. Additionally, Si‐rich mesostasis consisting of fine‐grained irregular quartz‐alkaline feldspar intergrowths suggests extreme fractional crystallization of the final few percent of melt. Shock textures indicate a moderate shock stage of approximately M‐S4. The discovery of NWA 13440 supports the model that many of the enriched shergottites are the martian equivalent of a continental flood basalt province.