Fate of mantle plume material trapped within a lithospheric catchment with reference to Brazil

Abstract

Local regions of thin lithosphere act as catchments of hot buoyant plume material. Unless replenished, the trapped plume material cools by convection to the mantle adiabat by several tens of million years. In particular, currently hot material from the ̃130 Ma, Paraná starting plume head is unlikely to supply 85 Ma to recent volcanism on the mainland of Brazil and the Martin Vaz and Fernando hot spots. Rather, a plume tail may now underlie southern Brazil where tomographic studies detect conduit-shaped velocity anomaly through the upper mantle. If the tomographic study in fact found a plume tail, the track crossed the Amazon rift at ̃85 Ma and (since then) lateral flow along thin regions of the lithosphere from the tail fed widespread feeble volcanism including the flow line hot spots of Martin Vaz and Fernando. © 2003 by the American Geophysical Union.