Blob Tectonics on Venus

Article excerpt

Blob tectonics on Venus

Planetary scientists have debated for more than a decade whether some form of the plate tectonics that shaped Earth also molded the surface of Venus. Now two researchers suggest that some of the most dramatic features on Venus result not from plate tectonics, but from a process they call "blob tectonics."

On Earth, the Hawaiian Islands and some other island chains represent one classic manifestation of plate tectonics. Such island chains apparently formed when a "hot spot" -- a plume of hot rock rising from the planet's interior -- broke through the crustal plate overhead. Over millions of years, towering volcanic peaks arose, which got carried away by the moving plate. As proposed by Robert R. Herrick and Roger J. Phillips of Southern Methodist University in Dallas, blob tectonics would involve gigantic, single "blobs" of hot materials rising like bubbles. These deformed and sometimes punched through a stationary Venusian surface, the Dallas scientists suggest.

Four examples of such blobs may underlie Aphrodite Terra, a hilly region that stretches at least 10,000 kilometers along Venus' equator, Herrick and Phillips say. Beta Regio, one of the first features on the planet identified as volcanic in origin, may kfber another candidate site for blob tectonics.

"A basic tenet of this model is that tectonism and magmatism [the formation of molten material] at Beta Regio and western Aphrodite are dominated by the evolution of plume heads or blobs as they rise to the base of the lithosphere and spread laterally," the authors write in the November GEOPHYSICAL RESEARCH LETTERS. …