Abstract

Extremely fresh Archean komatiite has been discovered near Zvishavane, Zimbabwe. The geochemistry of these rocks opens a window to the Archean mantle and will have profound implications on geophysical and geochemical models of early Earth. In the rocks, olivine is largely pristine and contains inclusions of fresh glass. Surface sampling and a 200-m drill hole have produced complete sections through a series of komatiite flows in which chill zones are preserved and which have MgO content of 17–20 wt%. Some alteration has taken place, but these are nevertheless among the freshest Archean rocks yet found.

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