Abstract:
Basalts occur as sub-alkaline tholeiites in the Naga
ophiolite belt. They bear an E-MORB affinity
ascribed to aqueous fluid addition from a dehydrating
oceanic crust in a supra-subduction zone during the
Indo-Burma plate collision. They are commonly
altered to spilite. They exhibit relatively poor REE
fractionation with almost flat chondrite-normalized
patterns. Eu-anomalies are not prominent, indicating
the negligible role of plagioclase fractionation in their
petrogenesis. Rock magnetic studies suggest that magnetite
is the major magnetic mineral in these Upper
Cretaceous basalts.
