The Lower Carboniferous Baralacha La basaltic dykes were emplaced along
transtensional faults. The basalts exhibit tholeiitic and alkaline
affinities. The tholeiites are TiO2-poor, moderately enriched in light
rare earth (LREE), and display Nb and Ta negative and Th positive
anomalies. The alkali basalts, compared to the tholeiites, have higher
TiO2, rare earth and highly incompatible trace element contents and
greater LREE enrichments. The Nd and Pb isotope compositions of the
Baralacha La basalts suggest that they derive from the partial melting
of an enriched OIB mantle source. characterized by a HIMU component, and
contaminated by the lower continental crust. The Baralacha La dyke swarm
represent the remnants of an early rifting event on the northern Indian
passive margin.