P, Cr, and Al zonation in komatiitic olivine

Abstract

The nearly ubiquitous presence in magmatic olivines of P zoning, often correlated with Cr and Al [1], suggests that these elements may help to clarify early stages of crystal growth that are otherwise inaccessible due to diffusive reequilibration of the dominant, divalent cations. Here, we describe zoning in olivine from unusually fresh, ~ 90 Ma komatiites of La Isla de Gorgona, Colombia [2, 3]. Komatiites are extreme among magmatic rocks in their ultramafic compositions; they are commonly thought to have high emplacement temperatures and a deep origin.

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