Petrological Characteristics and Genesis of the Central Indian Ocean Basin Basalts

作者：Das Pranab^*; Iyer Sridhar D; Hazra Sugata

来源：Acta Geologica Sinica, 2012, 86(5): 1154-1170.

DOI：10.1111/j.1755-6724.2012.00738.x

• basalts
• Genesis
• Central Indian Ocean Basin

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 (similar to 1018 wt%) and TiO2 (similar to 1.42.7 wt%) indicating a ferrobasaltic composition. The basalts have high incompatible elements (Zr 63-228 ppm; Nb similar to 1-5 ppm; Ba similar to 15-78 ppm; La similar to 316 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 mid-oceanic ridge basalt (similar to 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.

• 出版日期2012-10