Rare earth element mobility and geochemical characterisation of spilitic rocks

Abstract

HELLMAN & Henderson1 have demonstrated the enrichment of the rare earth elements (REE) in the lower spilitic portion of the Bhoiwada lave profile relative to the fresh tholeiitic flow top. The remarkable feature of the REE distribution in the spilites was the absolute enrichment of all the elements and not only the light REE, as occasionally seen in oceanic basalts due to submarine weathering2. Thus the enhanced spilite REE destribution resembles either alkali basalt or tholeiitic differentiation products rather than tholeiitic basalt. As stated1, the high degree of REE mobility suggests that these elements must be used with caution in determining the initial magma type or volcanic environment of ancient spilitic rocks.