Abstract

The macrodikes of the east Greenland Tertiary igneous province partially melted Precambrian basement along their contacts. Field evidence suggests that silicic liquid produced by partial melting of the basement buoyantly migrated roofward in the intrusions, where it ponded, and kinetic and/or rheological barriers prevented the crustderived melt and mafic magma of the macrodikes from intimately mixing. However, extensive redistribution of mobile elements occurred locally between these reservoirs. Close agreement between element partitioning in the various lithologic units in the macrodikes and experimental observations involving liquid immiscibility and silicate liquid interdiffusion suggests that chemical equilibrium between the magma reservoirs was approached through diffusive element exchange.

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