T.V. Romanyuk

Schmidt Institute Physics of the Earth RAS, Moscow 123995, B.Gruzinskaya 10

A short schematic description of the major Cenozoic events taken place into the western part of the Northern American continent and been acompained a proceses of transformation a convergent continental margin into a transform plate boundary is present. The Cenozoic geodynamic evolution has greatly influenced the present day tectonic provinces. The summary of various geological-geophysical data allowed to compile an integrated geological-geophysial model along "W-USA" profile crossing contrast lithospheric structures of the Western USA related both to upwelling, and downwelling mantle flows. Results of seismic-gravity modeling for "W-USA" profile testify that the upper mantle anomalies can not be generated by purely thermal processes, the important role in their genesis belongs to petrological/metamorphic transformations (including a partial melting).