Chemical clues to the origin of basic fragments embedded in a basaltic suite of the precambrian metamorphic terrain of Singhbhum,Eastern India

Pyroclastic fragments of basaltic composition are obtained in a thick metabasaltic layer from the Singhbhum orogenic belt of Eastern India. Field relations indicate the basalts to be submarine lava flows. Chemically, the metabasalts represent an original dry basaltic magma, showing a differentiation trend of Fe-enrichment much like the abyssal tholeiites and the Skaergaard rocks. The fragments are sharply angular in shape and distinctly richer in FeO, MgO, and MnO relative to the enclosing matrices. It is shown that the fragments are least likely to represent solidified lavas. These are best explained as cumulates which were fragmented and erupted with the fractionated melts.