Basalts forming the floor of the Indian Ocean are geochemically distinct from those of the Atlantic and Pacific Oceans. These differences have been attributed to a deeply recycled continental component or to widespread dispersion of plume-type mantle within the Indian Ocean asthenosphere. The discovery of Proterozoic continental crustal rocks within the uppermost basaltic basement of Elan Bank, part of the Kerguelen Plateau, shows instead that direct shallow-level contamination of basaltic magmas by isolated continental crust fragments may have produced the anomalous isotopic ratios of some Indian Ocean basalts.

87Sr/88Sr values are normalized to 86Sr/88Sr = 0.1194. The average value of NBS 987 over the course of the study is 0.710272+/-0.000009 (n = 45). 143Nd/144Nd values are normalized to 146Nd/144Nd = 0.7219. The average value of Merck Nd standard over the course of this study is 0.511963+/-0.000009 (n = 64). Pb isotropic ratios are corrected by a factor of 1.0007 per atomic mass unit for mass fractionation on the basis of repeated analyses of the standard NBS 981. 206Pb/204Pb and 207Pb/204Pb are measured with a precision of 0.1‰ and 208Pb/204Pb of 0.15‰.

Supplement to: Weis, Dominique A M; Ingle, Stephanie; Damasceno, Dimitri; Frey, Frederick A; Nicolaysen, Kirsten P; Barling, Jane; Shipboard Scientific Party (2001): Origin of continental components in Indian Ocean basalts: Evidence from Elan Bank (Kerguelen Plateau, ODP Leg 183, Site 1137). Geology, 29(2), 147-150