January 25, 2001 -- Following are highlights from the February issue of GEOLOGY and a summary of the science article from the February issue of GSA TODAY, published by the Geological Society of America. Stories written regarding these articles are embargoed until February 1. We ask that you discuss articles of interest with the authors before publishing stories on their work, and that reference be made to GEOLOGY or GSA TODAY in stories published. Please contact Ann Cairns at GSA to request advance copies of articles and for additional information or assistance.
GEOLOGY
Chaos on Io: A model for formation of mountain blocks by crustal heating, melting, and tilting. William B. McKinnon, et al. Recent Galileo images show that most of Io's mysterious mountains are tilted blocks undergoing tectonic collapse. McKinnon and coauthors propose a model in which Io's continuous volcanism and terrain burial (driven by very strong tidal heating) naturally lead to such unstable topography - primarily by creating very large confining stresses as older crust subsides and heats up and expands - causing thrust faulting. In essence, Io's copious volcanism can create a thick crust, but volcanic conditions are unstable and lead to breakup and tilting of this crust and thus towering mountains. This helps explain why concentrations of mountains are seen on Io that are separated from concentrations of volcanoes. Strong tidal heating and crustal disruption are also seen on the neighboring moon Europa, creating what are called "chaos regions." Similarly, concentrations of mountains on Io can be viewed as examples of "chaos on Io."
Did glaciation trigger intraplate seismicity in the New Madrid seismic zone? Balz Grollimund and Mark D. Zoback
In our article we investigate whether the melting of the last ice sheet could be responsible for the anomalous seismicity in the New Madrid area, eastern central United States. This area has been exposed to l
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Contact: Ann Cairns
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Geological Society of America
24-Jan-2001