Geochemistry and petrogenesis of tholeiitic dykes from the Chotanagpur Gneissic Complex, eastern India

Geochemical analysis on 14 samples from seven distinct E–W trending mafic dykes from the Chotanagpur Gneissic Complex. These dykes are characterised as basalt and basaltic andesite and comparable with E-MORB type tholeiitic magma series. The dykes are classified into two groups, low Mg# and high Mg# dykes, based on their Mg# and silica content. The major fractionating mineral phases are olivine, plagioclase, and pyroxene. The dykes are variably contaminated with crustal input and also underwent post-magmatic hydrothermal alteration after their emplacement. Semi- quantitative trace element modelling suggests that these dykes are derived by partial melting within spinel peridotite-rich mantle and spinel–garnet peridotite-rich mantle source in the transition zone. The low Mg# dykes are consistent with 3–15% partial melting curves, whereas high Mg# dykes are comparable with 15% melting curve.

Citation: RAHUL PATEL, RAVI SHANKAR, D SRINIVASA SARMA  and AUROVINDA PANDA, 2021. J. Earth Syst. Sci. 130:160, external link