Arctic lithospheric structure from delays of teleseismic P-wave reflections

Abstract

Differential (PP-P) travel-time residuals can indicate anomalous structure near the PP reflection points. Published teleseismic data are used here to cover parts of the Arctic Ocean, northern Eurasia and Greenland. Reflection residuals can be correlated with known lithospheric structure, and the interpretation may be extended to regions which are less well understood, especially the Arctic Ocean. Late reflections (several seconds two-way delay) occur along parts of the Alpha and Lomonosov Ridges, and under much of the East Siberian Shelf. These could be due to hotter regions of the lithosphere, and a mantle hot spot may exist on the Lomonosov Ridge near the North Pole. The Nansen Ridge (spreading center) does not give the expected late reflections, and may be displaced from the convection cell boundary in the upper mantle. The onshore shield areas give early reflections, and negative residuals also tend to occur for reflections under part of the Paleozoic Ural Geosyncline. A hot spot may have been located under Baffin Bay, and is probably not connected with Tertiary vulcanism in east Greenland.