Generation of nordmarkitic melts by melting of basement gneisses: the Astrophyllite Bay complex, Kangerdlugssuaq

Abstract

Acid-basic net-veined or pillowed dykes and intrusive bodies are small but important components in the felsic complexes of the Tertiary magmatic province in East Greenland. In Astrophyllite bay in the Snout Series syenite intrusion at the margin of the Kangerdlugssuaq syenite intrusion basic trachyandesite melis invade and melt the host of Archaean granitic gneisses. Pillows of trachyandesite are chilled to the surrounding felsic anatectic melt. Tue felsic melt is not granitic but syenitic in composition. Element distributions between the chilled basic and felsic melts suggest that the anatectic melt was transformed to a syenitic composition by diffusion between the two contacting melts.