¹Abdelmadjid Seddiki, ²Bertrand Moine, ³Jérôme Bascou, ¹Ratiba Kared, ³Jean Yves Cottin, ⁴Marguerite Godard, ⁵François Faure, ⁶Richard C. Greenwood, ¹Ian A. Franchi
Chemie der Erde (Geochemistry) (in Press) Link to Article [https://doi.org/10.1016/j.chemer.2025.126363]
¹Laboratoire Géoressources, Environnement et Risques Naturels (GEOREN), Université d’Oran2, BP: 1510, Oran, 31000, Algeria
²Laboratoire Magmas et Volcans, F-63000, CNRS, IRD, OPGC, Université Clermont Auvergne, Clermont-Ferrand, France
³Université Jean Monnet, CNRS, LGL-TPE, UMR5276, F-42023, Saint-Etienne, France
⁴Géosciences Montpellier, Université Montpellier II, Place Eugène Bataillon, 34095, Montpellier, cedex5, France
⁵CRPG, Université Henri Poincaré de Nancy, 15, rue Notre-Dame des Pauvres, B.P. 20, 54501, Vandoeuvre-lès-Nancy, France
⁶Planetary and Space Sciences Research Institute, Open University, Milton Keynes, MK7 6AA, UK
Copyright Elsvier

Northwest Africa (NWA) 4269 is an anomalous monomict eucrite that is characterized by a very high content of metallic iron (~ 3 %). It shows various textures (relict magmatic sub-ophitic, granulitic areas as coarse and fine-grained). NWA 4269 also shows petrographic evidence of secondary sub-solidus reheating events. Pyroxenes have homogeneous compositions and are iron-rich. NWA 4269 is metamorphosed type 5. It has a normal HED oxygen isotope composition. The chemical composition of NWA 4269 has characteristics similar to that of Nuevo-Laredo trend eucrites. Metal is extremely abundant in the fine-grained areas (~ 10 %). Metal also has a very low Ni content (Ni < 0.1 %) that excludes a direct origin from a chondrite-like impactor. Origin of the pure-Fe groundmass metal remains enigmatic. The high metal content in NWA 4269 can be interpreted as having formed via the reduction of FeO and probably also by desulfidation of pre-existing troilite. Iron metal could have formed by deposition from a Fe-rich fluid that, probably after an event that triggered sudden reduction. NWA 4269 has normal HED oxygen isotope compositions and interpreted as belonging to the 4-Vesta asteroid.