EHRC Homepage | New Category | Your Questions

David Tyler replies:

This is an interesting set of data - which must mean something! The problem for earth scientists is: how should this trend be interpreted?

As an alternative to the Plate Tectonic model, consider that developed by Warren Carey (Professor Emeritus of geology in the University of Tasmania). I refer to his book "Theories of the Earth and Universe", Stanford University Press, 1988.

His analysis is one which promotes the concept of tectonic control. He reconstructs the Pacific Floor in terms of age provinces and shear zones. The Hawaiian ridge runs parallel to the Melanesian Plateau, and the Emperor Ridge runs parallel to the Mariana Ridge. He calls the gap between the the Hawaiian Ridge and the MP the "Central-Pacific Sphenochasm" and the gap between the Emperor Ridge and the Mariana Ridge the "Shatsky Spenochasm". By applying a dextral global torsion (by 34 degrees) he closes these chasms. These changes are all linked to Tethyan widening. In this model, hot spots are not required, and the volcanism is mainly contemporaneous.

Carey writes:

"Plate tectonicists place much emphasis on the decrease in the ages of the volcanic rocks along the Emperor and Hawaiian ridges, and interpret them in terms of motion of the Pacific "plate" over a "hotspot" fixed in the mantle. But these ages record the times at which volcanism _terminated_. The lavas at Hawaii are 12 km thick. I suggest that the lava at the base is very much older than those measured at the surface, perhaps as old as any in the Emperor Ridge." (page 321).

The least that can be said about this is that there is here an alternative model - and I am a great believer in the evaluation of multiple models! I wonder how many geoscientists have considered Carey's explanation?

______________________________________________________ Ó 2010 Arthur V. Chadwick, Ph.D.