Petrography and geochemistry of a newly discovered Martian gabbroic shergottite NWA 16254

The Martian meteorite North-west Africa (NWA) 16254 is classified as a gabbroic shergottite, representing the first documented geochemically depleted member of this textural group. This coarse-grained cumulate comprises pyroxenes (augite and pigeonite), maskelynite, and accessory phases, exhibiting a two-stage crystallization history: 1) early high-pressure formation of Mg-rich pyroxene cores (4.3–9.3 kbar) at the Martian mantle‒crust transition zone, followed by 2) shallow crustal crystallization (< 4 kbar) of Fe-enriched pyroxene rims and plagioclase. Geochemical analyses reveal a depleted shergottite signature characterized by pronounced light rare earth element (LREE) depletion and redox conditions indicative of a reduced mantle source. The oxygen fugacity (fO2) calculated via pigeonite-core Eu oxybarometry yields IW − 1.0 ± 0.2, corroborated by late-stage Ti3+-bearing ilmenite assemblages, which reflect sustained reducing conditions during crystallization.The bulk-rock major element compositions and Mg# values closely align with the depleted shergottite Queen Alexandra Range (QUE) 94201, suggesting a potential cognate origin from a shared magma system. The gabbroic texture and protracted crystallization history of NWA 16254 provide critical insights into prolonged magma chamber evolution within the Martian crust, implicating episodic melt extraction from a long-lived, incompatible element-depleted mantle reservoir. These findings redefine textural diversity among depleted shergottites and underscore the need for geochronological studies to resolve temporal links between ancient mantle processes and Amazonian magmatism.