Lawsonite-omphacite-bearing metabasites of the Pam Peninsula: NE New Caledonia: Evidence for disrupted blueschist- to eclogite-facies conditions

Abstract

The Diahot terrane of NE New Caledonia contains an inter-bedded sequence of Cretaceous to Eocene metasediments, felsic and mafic metavolcanics that experienced c. 40 Ma high-P/T metamorphism. Metabasaltic assemblages define two prograde events (M1 and M2) and a tectonically disrupted crustal profile that extends from lawsonite-blueschist conditions in the SW to paragonite-eclogite conditions in the NE. Weakly deformed metabasalts from lowest-grade parts of the Diahot terrane contain M1 omphacite, chlorite, lawsonite and glaucophane-bearing assemblages that partially pseudomorph igneous plagioclase and augite, and reflect P = 0·7-1·0 GPa and T = 350-400°C. M1 assemblages are enveloped by a st..