Forsteritic olivine in EH (enstatite) chondrite meteorites: a record of nebular, metamorphic, and crystal-lattice diffusion effects

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dc.contributor.authorHuber, Matthew
dc.contributor.authorMcKibbin, Seann J
dc.contributor.authorHecht, Lutz
dc.contributor.authorMakarona, Christina
dc.date.accessioned2025-01-17T09:39:09Z
dc.date.available2025-01-17T09:39:09Z
dc.date.issued2024
dc.description.abstractThe occurrence of forsteritic olivine in EH enstatite chondrites is indicative of bulk disequilibrium. In MgO-rich magmatic systems, forsterite can either crystallize as a liquidus phase or be produced during peritectic melting of enstatite. Because diffusion of divalent cations through forsterite is relatively rapid, it records peak melting (i.e., chondrule-forming events) and is also sensitive to subsequent metamorphism in the EH chondrite parent body. Here, we report the major and minor element geochemistry of olivine in EH chondrites across petrologic types 3 and 4. In all cases, olivine meets the technical definition of forsterite (>90 mole% Mg2SiO4). For unequilibrated EH chondrites, minor elements identify CaO-Al2O3-TiO2-rich (refractory forsterite), MnO-rich (“LIME” forsterite), and FeO-bearing (forsteritic olivine) endmember components, the latter with Cr2O3-rich and Cr2O3-poor varieties. At higher petrologic type, minor element concentrations become restricted and compositions approach pure forsterite, while grain sizes reduce strongly with peak metamorphic temperatures. These changes reflect diffusive equilibration with enstatitic groundmass and dissolution reaction with free silica. The global geochemical distribution of forsteritic olivine in EH chondrites is, perhaps unexpectedly, more similar to those in low-FeO type I chondrules and associated objects in carbonaceous chondrites (CCs), rather than equivalent objects in ordinary (H, L, LL), low-FeO (or HH), or Kakangari (K) chondrites.
dc.identifier.citationMcKibbin, S.J., Hecht, L., Makarona, C., Huber, M., Terryn, H. and Claeys, P., 2024. Forsteritic olivine in EH (enstatite) chondrite meteorites: A record of nebular, metamorphic, and crystal‐lattice diffusion effects. Meteoritics & Planetary Science.
dc.identifier.urihttps://doi.org/10.1111/maps.14147
dc.identifier.urihttps://hdl.handle.net/10566/19812
dc.language.isoen
dc.publisherWiley
dc.subjectforsteritic olivine
dc.subjectchondrite parent body.
dc.subjectenstatitic groundmass
dc.subjectcarbonaceous chondrites
dc.subjectmagnesian xenocrystic
dc.titleForsteritic olivine in EH (enstatite) chondrite meteorites: a record of nebular, metamorphic, and crystal-lattice diffusion effects
dc.typeArticle

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