Geophysics

The Rise of the East

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Science  25 Jul 2003:
Vol. 301, Issue 5632, pp. 438
DOI: 10.1126/science.301.5632.438a

An early confirmation of plate tectonics theory was the finding of symmetrical magnetic anomalies on both sides of mid-ocean ridges. More recent studies, however, have suggested that rift zones can sport substantial asymmetry. Examining bathymetric profiles for 20 representative rift sections, Doglioni et al. have found that the eastern sides of the East Pacific Rise, the Mid-Atlantic Ridge, and the northwest Indian Ridge are all 100 to 300 m higher than the western sides. Moreover, the eastern flanks of continental rift zones, such as the Red Sea and Lake Baikal, are likewise uplifted relative to the western flanks. The asymmetry may stem from a global “westward drift” of the strong lithosphere relative to the underlying, more plastic mantle. Such drift would cause the depleted, buoyant asthenosphere (generated by partial melting below mid-ocean ridges) to be shifted relatively eastward beneath the lithosphere, which would then lift the eastern flanks. The same mechanism may have contributed to the anomalous uplift of the tectonically stable African continent since the Mesozoic. — SW

Tectonics 10.1029/2002TC001459 (2003).

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