Rb‐Sr and Sm‐Nd isotopic and <scp>REE</scp> studies of igneous components in the bulk matrix domain of Martian breccia Northwest Africa 7034

<jats:title>Abstract</jats:title><jats:p>The bulk matrix domain of the Martian breccia <jats:styled-content style="fixed-case">NWA</jats:styled-content> 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia. Both <jats:sup>147</jats:sup>Sm‐<jats:sup>143</jats:sup>Nd and <jats:sup>146</jats:sup>Sm‐<jats:sup>142</jats:sup>Nd age results for mineral separates from the bulk matrix portion of breccia <jats:styled-content style="fixed-case">NWA</jats:styled-content> 7034 suggest that various lithological components in the breccia probably formed contemporaneously ~4.44 Ga ago. This old age is in excellent agreement with the upper intersection ages (4.35–4.45 Ga) for U‐Pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous‐textured clasts. Consequently, we confirm an ancient age for the igneous components that make up the <jats:styled-content style="fixed-case">NWA</jats:styled-content> 7034 breccia. Substantial disturbance in the Rb‐Sr system was detected, and no age significance could be gleaned from our Rb‐Sr data. The disturbance to the Rb‐Sr system may be due to a thermal event recorded by bulk‐rock K‐Ar ages of 1.56 Ga and U‐Pb ages of phosphates at about 1.35–1.5 Ga, which suggest partial resetting from an unknown thermal event(s), possibly accompanying breccia formation. The <jats:styled-content style="fixed-case">NWA</jats:styled-content> 7034 bulk rock is <jats:styled-content style="fixed-case">LREE</jats:styled-content> enriched and similar to <jats:styled-content style="fixed-case">KREEP</jats:styled-content>‐rich lunar rocks, which indicates that the earliest Martian crust was geochemically enriched. This enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on Mars that have been detected in studies of other Martian meteorites.</jats:p>