In a landmark discovery published in the inaugural issue of Planet , a cutting-edge journal dedicated to planetary science, researchers from Chengdu University of Technology have unveiled the petrogenetic history of a newly identified Martian meteorite—Northwest Africa (NWA) 16254 (Fig. 1). This gabbroic shergottite, the first geochemically depleted member of its textural group, offers unprecedented insights into Mars’ volcanic processes and mantle-crust interactions, bridging critical gaps in understanding the planet’s magmatic diversity.
Led by Dr. Jun-Feng Chen of the Research Center for Planetary Science, the team combined advanced mineralogical mapping and geochemical analyses to decode the meteorite’s two-stage crystallization history. The study reveals that NWA 16254 formed initially under high-pressure conditions (4.3–9.3 kbar) at the Martian mantle-crust boundary, where magnesium-rich pyroxene cores crystallized. Later, the magma ascended to shallow crustal depths (<4 kbar), where iron-enriched pyroxene rims and plagioclase developed. This prolonged cooling process, preserved in the meteorite’s coarse-grained texture, suggests episodic melt extraction from a long-lived, depleted mantle reservoir—a critical clue for reconstructing Mars’ magmatic evolution.
The meteorite’s geochemical depletion, marked by light rare earth element (LREE) depleted (Fig. 2) and low oxygen fugacity ( f O 2 =IW−1.0), aligns it with the rare QUE 94201 meteorite, hinting at a shared magma source. Its gabbroic texture, indicative of slow cooling in crustal chambers, distinguishes it as a unique archive of subsurface magmatism. These findings challenge existing models of Martian volcanic evolution, as NWA 16254’s consistently low f O 2 , corroborated by Ti 3+ -bearing ilmenite assemblages, implies sustained reducing conditions during crystallization. This underscores the heterogeneity of Mars’ mantle and raises questions about the planet’s redox evolution over billions of years. Future geochronological studies could resolve whether this meteorite represents ancient mantle melting (~2.4 billion years ago) or younger magmatic activity, offering clues to Mars’ thermal history.
The study leverages state-of-the-art techniques, including TESCAN Integrated Mineral Analyzer (TIMA) mapping and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), to trace mineral zoning and trace element distributions. These methods revealed decoupled geochemical behaviors in pyroxene cores and rims—a phenomenon critical for reconstructing magma chamber dynamics. For researchers, NWA 16254’s well-preserved geochemical signatures present a prime target for isotopic analyses, potentially unlocking timelines of Martian mantle depletion and refining models of planetary differentiation.
Planet
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Petrography and geochemistry of a newly discovered Martian gabbroic shergottite NWA 16254
13-May-2025