14. TRACE ELEMENT GEOCHEMISTRY OF BASALTIC ROCKS RECOVERED AT SITE 516, RIO GRANDE RISE, DEEP SEA DRILLING PROJECT LEG 721

The geochemistry of basalts recovered during Leg 72 is described with emphasis on trace elements. Only Hole 516F penetrated basement; the basalts recovered are plagioclase-phyric and olivine-phyric and pervasively altered. Chemical-ly, the basalts from Hole 516F are rather uniform in composition. However, four distinct geochemical units can be recognized, although the chemistry of two of the units appears to be controlled by chemical mobility associated with al-teration. The two less-altered units cannot be related by fractional crystallization processes. Hole 516F basalts have a trace element chemistry characteristic of T-type mid-ocean ridge basalt; rare-earth element patterns (as indicated by Ce/ Y ratios) are mildly fractionated flight rare-earth element enriched), and a number of incompatible element ratios are close to chondritic