Summary of the Wilson cycle
The Wilson cycle begins in Stage A with a stable continental Craton. A hot spot rises up under the Craton, heating it, causing it to swell upward, stretch and thin like taffy, crack, and finally split into two pieces. This process not only splits a continent, it also creates a new divergent plate boundary (see Rift Model).
In Stage B, the one continent has been separated into two continents, east and west, and a new ocean basin (the Ophiolite Suite) is generated between them. The ocean basin in this stage is comparable to the Red
Sea today. As the ocean basin widens the stretched and thinned edges where the two continents used to be joined cool, become denser, and sink below sea level. Wedges of divergent continental margin sediments accumulate on both new continental edges.
Stage C - the ocean basin widens, sometimes to thousands of miles; this is comparable to the Atlantic ocean today.
Stage D - the closing phase of the Wilson cycle begins when a subduction zone (new convergent plate boundary) forms. The subduction zone may form anywhere in the ocean basin. In this model we take the simplest situation; a subduction zone developing under the edge of one continent. Once the subduction zone is active the ocean basin will eventually disappear. These are remnant ocean basins.
Stage E - most of the remnant ocean basin has subducted and the two continents are about to collide. Deep in the subduction zone igneous magma is generated and rises to the surface to form volcanoes, that build into a cordilleran mountain range (e.g. the Cascade mountains of Washington, Oregon, and northern California.) Also, metamorphism, folding and faulting occurs (Mountain Building Models)
Stage F - the two continents, separated in Stages A and B, now collide. The remnant ocean basin is completely subducted. Technically the closing phase of the Wilson cycle is over. Because the subduction zone acts as a ramp the continent with the subduction zone (a hinterland) slides up over the edge of the continent without it (a foreland).
Stage G - once the collision has occurred the only thing left for the mountain to do is erode down to sea level - a peneplain. The Stage G drawing is distorted; with the collision the continental thickness doubles, and since continental rock is light weight, both will rise as the mountain erodes.
Contributed by Lynn Fichter