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Global Plate Reorganization

Rona & Richardson (1978) present evidence that supports the hypothesis of Anderson (2002). This hypothesis suggests that fluctuations in stress in the lithosphere are responsible for global plate reorganizations and evolution of volcanic chains. Rona & Richardson (1978) present compelling evidence for forced feedback from the plates to mantle convection cells. The E-W length of N-S converging continent-continent collisional plate boundaries increased from 2,500 to 28,000 km during the interval 55 - 40 Ma, and remains at about 19,000 km. We infer that this increase in length of collisional boundaries produced resistance to continued N-S convergence and forced reorientation of plate motions. Large N-S components of most resistance to motion, and large E-W components of least resistance, became the dominant pattern. Our evidence for a change to a dominant E-W component of motion comprises continuation of pre-exsiting E-W spreading, initiation of new E-W seafloor spreading, an increase in length of subduction zones along convergent plate boundaries to accommodate the spreading, deceleration of spreading rates, and obduction of ophiolites as a product of plate reorganization.

Global plate organizations have probably occurred throughout most of geologic history. The Eocene reorganization is exceptional in that nearly the entire record is preserved in magnetic lineations, hot spot trends (including the Emperor Seamount-Hawaiian Ridge bend), collisional mountain belts, and ophiolites. For this reason, the Eocene reorganization provides clear evidence of how the plate system actually works.

References

  • Anderson, D.L., Plate tectonics as a far-from-equilibrium self-organized system. in S. Stein and J.T. Freymueller, Editors, Plate Boundary Zones, Am. Geophys. Un., Geodynamics Series, v. 30: 411-425, 2002.
  • Rona, P.A., and E.S. Richardson, Early Cenozoic global plate reorganization, Earth Planet. Sci. Letters, 40: 1-11, 1978.

Peter A. Rona, Ph.D., Professor of Marine Geology and Geophysics
Institute of Marine and Coastal Sciences
Rutgers University
71 Dudley Road
New Brunswick, New Jersey 08901-8521
Phone: 732/932-6555 x 241
Fax: 732/932-6557
Email: rona@imcs.rutgers.edu

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