Trace element characteristics of lavas from destructive plate boundaries.

Abstract

Volcanic-arc basalts are all enriched in incompatible elements of low ionic potential, probably due to influx of aqueous fluids from subducted oceanic crust into their mantle source-regions. Island- arc basalts are also characterized by low abundances of incompatible elements of high ionic potential. Calc-alkaline basalts and shoshonites are further characterized by enrichment in Th, P, and light RE in addition to elements of low ionic potential. Plots of Y vs Cr, K/Yb, Ce/Yb, or Th/Yb vs Ta/Yb, and Ce/Sr vs Cr enable volcanic-arc basalts to be recognized when the geological evidence is ambiguous. Such plots are applied to lavas from the Oman ophiolite complex. -A.H.