THE MOTION AND BOUNDARY BETWEEN THE CAPRICORN AND AUSTRALIAN PLATES

The motions between the Somalian, Antarctic, and Australian plates-the three plates believed to meet at the Rodrigues triple junction in the Indian Ocean-are inconsistent with the assumption that all three plat es are rigid. The discrepancy is best explained if the Australian plat e contains two component plates. Thus, the traditionally defined Indo- Australian plate consists of three component plates and multiple diffu se plate boundaries. The pattern of present deformation indicates that the boundaries between the th ree component plates are two unconnecte d zones accommodating divergence and a larger zone, which we interpret as three diffuse convergent plate boundaries and a diffuse triple jun ction.