Compositions, stratigraphy, and alteration of pillow basalts, Deep Sea Drilling Project hole 543A, near the Barbados Ridge.

Abstract

At the top of the basalts, plagioclase is replaced by K-feldspar with K2O contents of 5%. The early oxidative alteration produced fractures lined with celadonite, dioctahedral smectite and replacement of olivine and intersertal glass with Fe-hydroxides and green clay minerals. Later non-oxidative alteration produced olive-green clays and pyrite veins. Finally, fractures and voids were filled with calcite at 12o-25oC, according to O-isotope determinations.-K.A.R.