THOLEIITIC DYKES IN THE SEYCHELLES AND THE ORIGINAL SPATIAL EXTENT OF THE DECCAN

We report geochemical data from c. Deccan age tholeiitic dykes from Praslin Island in the Seychelles, a continental fragment which lay adjacent to the coast of India before sea-floor spreading started in the Arabian Sea at 64 Ma. The dykes have compositions very similar to the distinctive Bushe magma-type from the Deccan, and hence constitute the first traces of Deccan activity recognized on the Seychelles. Fitting the Seychelles and India back together to reconstruct the original extent of the Deccan, we find that the present estimate of 1 million km2 needs to be revised upwards by c. 25% to account for the Deccan magmatism in the Seychelles. If dipping reflectors found on seismic lines to the northwest of the Seychelles are also Deccan age flows, this would increase still further the area and volume estimates.