Geochemistry of basic dykes from Betul-Jabalpur area in the Deccan volcanic province

Dykes exposed in the Betul-Jabalpur area, lie parallel to E-W trending Narmada-Son and Tapti lineaments in the Deccan volcanic province. These dykes show a variety of textural features and contain plagioclase (33-45%), clinopyroxene, olivine, magnetite and glass. These dykes are mainly basalt and basaltic andesite. Betul-Jabalpur and Tapti dykes show increase in sub-alkalis (K2O+Na2O) with the rise in SiO2 values. Their data plots confine to the subalkalic array suggesting fractional crystallization as the dominant process. The high field strength elements in these dykes also show close correlation with the dykes south of the Tapti valley. Low concentration of Rb, Ba and V in Betul-Jabalpur dykes indicate that they are less contaminated than the other dykes of Deccan volcanic province. The large-scale chemical similarity in the major and trace elemental composition of the Betul-Jabalpur and south of Tapti valley dykes suggests their origin from a common magma type, possibly derived from the fractionation of isolated high gravity mafic-ultramafic igneous bodies positioned 6-8 km below the surface, trending parallel to the Narmada-Tapti rift zone.