Pot Shots at Hot Spots

first_imgSay that title five times, and you’ll be as flummoxed as geologists reporting in Science1 last week that long-believed assumptions are wrong.  They looked at three seamount chains in the Pacific, long thought to provide evidence of tectonic plates moving across stationary hot spots, and found that current theory cannot account for them:Our findings influence our views of oceanic intraplate volcanism and absolute Pacific plate motion: (i) The textbook explanation for intraplate volcanism by fixed hot spots is either entirely wrong or insufficient to explain these phenomena.  (ii) Hot spots are likely not to be stationary, but move with the convecting mantle.  (iii) Non-hot spot/plume models have to be considered for explaining intraplate volcanism, whereby local lithospheric extensions are likely to be an important candidate.  (iv) Furthermore, absolute Pacific plate motion, for the time period between 80 and 47 Ma, is extremely poorly constrained.  It is not clear if any of the three HEB-type bends on the Pacific plate are caused by a change in plate-motion direction, and it is similarly uncertain if the plate moved NW (along an extended Hawaiian trend) or NNW as indicated by the Emperor seamount trail.   (Emphasis added in all quotes.)Their three alternative explanations were only tentative: “Overall, plate extension is the strongest alternative among our three options, but there are very few arguments or clues that positively identify any particular explanation.”1Koppers and Staudigel, “Asynchronous Bends in Pacific Seamount Trails: A Case for Extensional Volcanism?”, Science, Vol 307, Issue 5711, 904-907, 11 February 2005, [DOI: 10.1126/science.1107260].What?  The textbooks are wrong?  But the pictures were so artistic, and the TV programs were so convincing, how could this be?  Take your pick: current theory is either entirely wrong or insufficient to explain the observations.    See also the 04/02/2004 and 11/02/2002 entries about the hotspot paradigm shift going on.  What this one adds is that there is no good replacement theory, and the admission “there are very few arguments or clues that positively identify any particular explanation.”  So shouldn’t the geological community be open to some fresh out-of-the-mainstream perspectives?(Visited 7 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img

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