Tectonic Evolution of Western North America |
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| Approaching ca. 10 MYA |
| As North America progressively overrode more segments of the Pacific Spreading Center, subduction of oceanic crust under North America diminished; the North American and Pacific Plates coupled and moved westward together. Approaching 10 MYA, the triple junction of North American, Pacific, and Farallon Plates had moved south near Jalisco, Mexico. Western North America passed westward over the presumed stationary mantle upwelling which drives the Pacific Spreading Center. |