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The Central Indian Ocean Basin (CIOB) basalts are plagioclase-rich, while olivine and pyroxene are very few. The analyses of 41 samples reveal high FeOT (～10-18 wt%) and TiO 2 (～1.4-2.7 wt%) indicating a ferrobasaltic composition. The basalts have high incompatible elements (Zr 63-228 ppm; Nb ～1-5 ppm; Ba ～15-78 ppm; La ～3-16 ppm), a similar U/Pb (0.02-0.4) ratio as the normal mid -oceanic basalt (0.16±0.07) but the Ba/Nb (12.5-53) ratio is much larger than that of the normal midoceanic ridge basalt (～5.7) and Primitive Mantle (9.56). Interestingly almost all of the basalts have a significant negative Eu anomaly (Eu/Eu*=0.78-1.00) that may have been a result of the removal of feldspar and pyroxene during crystal fractionation. These compositional variations suggest that the basalts were derived through fractional crystallization together with low partial melting of a shallow seated magma.
The analyzes of 41 samples reveal high FeOT (~ 10-18 wt%) and TiO 2 (~ 1.4-2.7 wt%) indicating that the Central Indian Ocean Basin (CIOB) basalts are plagioclase-rich, while olivine and pyroxene are very few a ferrobasaltic composition. The basalts have high incompatible elements (Zr 63-228 ppm; Nb ~ 1-5 ppm; Ba ~ 15-78 ppm; La ~ 3-16 ppm) a similar U / Pb (0.02-0.4) ratio as the normal mid-oceanic basalt (0.16 ± 0.07) but the Ba / Nb (12.5-53) ratio is much larger than that of the normal midoceanic ridge basalt (~ 5.7) and Primitive Mantle (9.56). Interestingly almost all of the the These compositional variations suggest that the basalts were derived through fractional crystallization together with low partial (Eu / Eu * = 0.78-1.00) that may have been a result of the removal of feldspar and pyroxene during crystal fractionation. melting of a shallow seated magma.