Reporting from the West Antarctic Rift

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Science  11 Jan 2002:
Vol. 295, Issue 5553, pp. 235
DOI: 10.1126/science.295.5553.235d

Our knowledge of the crust and upper mantle that lie under Earth's continents is poorest in the Southern Hemisphere, particularly beneath Antarctica. This region is important tectonically because Antarctica contains major crustal provinces and because rifting around Antarctica was instrumental in the formation of all of the major ocean basins. Recent volcanism and rifting may also be influencing the stability of the major ice sheets there.

Ritzwoller et al. have produced a new tomographic map of the upper mantle structure beneath Antarctica and the Southern Ocean using surface wave velocities. Their model implies that the mantle beneath eastern Antarctica transmits seismic waves rapidly (or is “fast”) and thus is probably relatively cold and stiff. In contrast, the mantle beneath western Antarctica is “slower,” and thus hotter, although not as slow as the regions at active, spreading ridges. This map is consistent with the presence of ongoing volcanism within a dormant rift zone. — BH

J. Geophys. Res., 10.1029/2001JB000179.

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