The Evolution of Plate Tectonics

A central problem in understanding the Earth system is the relationship
between mantle convection and near-surface structure, geophysics and
geochemistry. Unexplained anomalies of the plate tectonics (PT) model are the
postulated mechanism of generating the axial rift valley by upward movement of
marginal fault blocks, contrary to observations in the Icelandic rift, and the
mechanism by which a postulated broad upwelling plume can yield the required
narrow zone of axial volcanism. These discrepancies are the basis for a
critical reappraisal of other evidence. It is shown that the generation of
oceanic magnetic stripes, which led to the ingenious spreading hypothesis, is
a result of narrowing of a formerly expanded ocean ridge volcanic system, and
resultant sequential cooling of crust and upper mantle, and does not require
ocean floor spreading. An alternative ridge model postulates sub-continent
upwelling, sub-ridge convergent flow and generation of mid-ocean ridge basalt
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