Evidence for a seismic discontinuity near 200km depth under a continental margin

We present evidence for a seismic discontinuity near 200km depth (the Lehmann Discontinuity) under the passive continental margin of north-west Australia, where continental lithosphere merges into oceanic lithosphere. The velocity contrast across the discontinuity is 0.2–0.3 km s−1, and is similar to the contrast across discontinuities at similar depths in seismic models for purely continental paths to the east under central Australia. The discontinuity has been shown to be present under continents, oceans and now at continental margins, and is probably a worldwide feature.