Petrological and Geochemical Studies on the Basalts of Mandla Lobe, Eastern Deccan Volcanic Province; Implications on the Shallow Melting of a Spinel Peridotite and Crustal Contamination

The petrological studies and geochemical analysis are carried out on the basalts of Mandla Lobe (MB), Madhya Pradesh of eastern Deccan Volcanic Province (EDVP) to evaluate their petrogenetic and tectonic evolution. These basalts are fine to be medium grained porphyritic and non-porphyritic composed of calcic plagioclase, clinopyroxene, altered olivine, chlorophaeite, opaque and glass showing a variety of intersertal, intergranular  textures indicating variable cooling histories and melt replenishment in a magma chamber. The MB samples exhibit tholeiitic trends evidenced by iron enrichment on AFM diagram. The La/Yb ratios of MB suggest relative enrichment of LREE over HREE without significant Europium anomalies. Low HREE ratios suggest that the precursor melts derived by low to moderate degree partial melting of a spinel peridotite mantle source. In the geochemical discrimination plots and discriminant function analysis, the MB correspond to the overlapping field between Poladpur and Ambenali Formations of Wai subgroup implying uncontaminated to significant crustal contamination.

Rb/Y vs Nb/Y plot for Mandla region basalts showing the geochemical correlations with the least contaminated Ambenali formation of the Western Ghat section of WDVP

Citation: K.N.S.S.S. Srinivas*, P. Pavan Kishore, K.S.V. Subramanyam and D.V. Subba Rao, 2021. JOURNAL GEOLOGICAL SOCIETY OF INDIA Vol.97, pp.843-858, DOI: 10.1007/s12594-021-1783-2