Petrochemistry of Basalt Flows of Chikhaldara Ghat Sections (District Amravati, Maharashtra)

S. D. Doke, P. S. Kulkarni, S. F. R. Khadri

Abstract: The ChikhaldaraGhat section of Amravati District situated towards North East part of Maharashtra, consisting of sixteen Basalt Flows, which are clearly exposed along the approach road to the hill station from R. L.600m to R. L.1092m. The major constituents of Chikhaldara Basalts are Ca-Plagioclase, Augite and small quantity of Olivine. The common accessory minerals in these flows are iron ores occurring as plates, rods, granules, needles and dust. Geochemistry of the flows is as below SiO2 (47.99 to 51.43 %), Al2O3 (12.17 to 15.51 %), Fe2O3 (13.59 to 16.02 %), MgO (4.12 to 6.81 %), CaO (8.00 to 12.06 %), Na2O (1.90 to 2.80 %), K2O (0.12 to 1.80 %) TiO2 (1.83 to 3.67 %), P2O5 (0.13 to 0.29 %) and MnO (0.18 to 0.24 %). Thus it is clear that they are enriched in Fe2O3 and TiO2 with lesser constituents of K2O and P2O5. The silica vs. alkali variation diagram indicates tholeiitic nature of lava flows. The plotting of MgOvs all major elements shows their relative abundance and relative trends. MgO decreases continuously during fractional crystallization of mafic liquids. The plotting of MgOvs. Al2O3, CaO and MnO show positive correlation whereas the plotting of MgOvs. Fe2O3 and TiO2 show negative trend which can be attributed to fractionationof Plagioclase, Clinopyroxene, with traces of Olivine.

Keywords: BasaltFlows, Mineralcomposition, variation diagram, Tholeiitic Lava, Fractional Crystallization