A subduction zone is formed at a convergent plate boundary when one or both of the tectonic plates is composed of oceanic crust. The denser plate, made of oceanic crust, is subducted underneath the less dense plate, which can be either continental or oceanic crust.hen one plate is composed of oceanic lithosphere and the other is composed of continental lithosphere, the denser oceanic plate is subducted, often forming an orogenic belt and associated mountain range. This type of convergent boundary is similar to the Andes or the Cascade Range in North America.
The San Andreas fault is one of only a few examples of a transform boundary between two tectonic plates that is exposed on a continent. Some other continental transforms are the Alpine fault in New Zealand and the Dead Sea Transform fault system in the Middle East.he remainder is expressed by displacement along other, subparallel faults such as the Imperial and the San Jacinto fault zones in southern California. The San Andreas fault zone is a transform boundary between two tectonic plates, the North America plate and the Pacific plate.
The San Andreas Fault in California is one example. 2. Divergent boundaries occur where two plates slide apart from each other. Mid-ocean ridges (e.g., Mid-Atlantic Ridge) and active zones of rifting (such as Africa's Great Rift Valley) are both examples of divergent boundaries.. Convergent boundaries (or active margins) occur where two plates slide towards each other commonly forming either a subduction zone (if one plate moves underneath the other) or a continental collision (if the two plates contain continental crust). Deep marine trenches are typically associated with subduction zones.