Quench Plagioclase from some Archean Basalts

Quench plagioclase has been recognized in well preserved Archean submarine basalts from four localities in the superior province of the Canadian Shield. The crystals are skeletal in form with hollow cross sections and swallow tail terminations. In some cases the microphenocrysts are zoned. The widespread occurrence of quench plagioclase suggests that this feature was rather common in Archean basalts, but it is only locally preserved.