Archaean megacrystic plagioclase units and the tectonic setting of greenstones

• Main Authors: Phinney, W. C., Morrison, D. A., Maczuga, D.
• Format: Other/Unknown Material
• Language: unknown
• Published: 1986
• Subjects: GEOPHYSICS; Ameralik
• Online Access: http://hdl.handle.net/2060/19860013651

Large (up to 20 cm), equidimensional, commonly euhedral, plagioclase megacrysts of highly calcic composition (An sub 80-90) occur commonly in all Archean cratons in one or more of three distinct associations: (1) as cumulate crystal segregations of anorthosite or as megacrysts in basaltic dikes, sil...