Petrology and geochemistry of oceanic intraplate sheet-flow basalts, Deep Sea Drilling Project Leg 89.

Abstract

The basalts are olivine- and quartz-normative tholeiites, characterized by low abundances of incompatible elements, moderate chondrite-normalized LIL element depletion patterns, and lower than or near-chondritic ratios for many incompatible element pairs. Three chemical megagroups and 22 subgroups are recognized that are interpreted to represent three separate low-P fractionation systems (olivine + plagioclase + or - clinopyroxene) with variable degrees of magma mixing and approach to steady-state conditions.-C.M.L.