Physical Sciences and Mathematics Commons^™

Mantle Layering Across Central South America, Kelly H. Liu, Stephen S. Gao, Paul G. Silver, Yongkai K. Zhang

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Imaging of seismic velocity discontinuities along a 3000 km profile across central South America at 20°S suggests that the depth variations of the 410-km (d410) and 660-km (d660) discontinuities are closely associated with the high-velocity Nazca slab and juxtaposed low-velocity oceanic mantle beneath the slab. The mantle transition zone thickness ranges from 220 km in the oceanic mantle to 270 km in a 600-km-wide area occupied by the deflected Nazca slab. The slab deflection has also been suggested by previous studies of seismic tomography and seismicity. This 50 km difference in the thickness corresponds to a lateral temperature variation of …