Wilson Cycle and Plate Tectonic Convergence

Wilson Cycle

1. Hot mantle materials rise, causing the crust to fracture due to its rigidity. The fractures allow magma to output, and blocks of the lithosphere move, initiating the formation of an intracontinental rift valley.
2. The expansion of the ocean floor creates a narrow sea.
3. The growth of the seafloor allows the development of a mature ocean basin. Stable continental margins are limited by the basin's floor, where an important place of sediment deposition occurs.
4. The stable continental margins become active when the oceanic lithosphere begins to sink in subduction.
5. The reduction of the ocean is very evident. Marginal ranges are formed on active continental margins.
6. The oceanic lithosphere continues to subduct and sink until the ocean is completely closed. Continents collide and originate a high intracontinental ridge. In the Tertiary period, the convergence of the Indian plate and the Eurasian plate closed a sea and started the uprising of the Himalayan mountain range.

Types of Convergence

Ocean-Ocean

One oceanic plate sinks beneath another oceanic plate in a process called oceanic subduction. The active plate is inserted down the passive plate following a variable tilt plane called the Benioff plane. An insular arc develops on the passive plate. The deepest oceanic trenches are located in the convex part of the insular arcs.

Ocean-Continent

The oceanic plate sinks beneath a continental plate at an angle of less than 90 degrees on the passive plate. Strong pressures cause a marginal range. The turning point of the active plate is where subduction occurs, extending around the convergent boundary's oceanic trenches.

Continent-Continent

A mixed continental plate faces the limit of another, also mixed. When the process ends, two continental blocks collide. One of them rides on the other in a mechanism called obduction, the reverse of subduction. The high pressures generated in these limits create an intracontinental mountain range.