See more from this Division: Topical Sessions
See more from this Session: Gondwana-Laurentia Terrane Transfers During the Pangean and Rodinian Supercontinent Cycles
Abstract:
This high temperature equilibration obtained for this metatroctolite, which is indistinguishable from magmatic temperatures, is consistent igneous crystallization followed by cooling at relatively high pressures of at least 0.8 GPa, which led to the reaction of olivine and plagioclase during cooling. Furthermore, the olivines have NiO compositions that vary from 0.1 to 0.4 wt. % at nearly constant Fo contents of 73-76, which is indicative of a cumulus origin for the olivine (Takahashi, 1991). Such forsterite contents are consistent with an equilibrium melt richer in Fe compared to mid-ocean ridge basalt, pointing to a high magnesium andesitic parental magma consistent with an island arc origin for the RLA. Calcium-rich compositions of plagioclases (An95-99) in the same metatroctolite are also consistent with an island arc origin for the RLA (e.g., Thy, 1987).
See more from this Division: Topical Sessions
See more from this Session: Gondwana-Laurentia Terrane Transfers During the Pangean and Rodinian Supercontinent Cycles