In a subduction zone, the subducting plate, which is normally a plate with oceanic crust, moves beneath the other plate, which can be made of either oceanic or continental crust. During collisions between two continental plates, large mountain ranges, such as the Himalayas are formed. Oceanic-continental.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.
Summary. Understanding the structure of silicate minerals makes it possible to identify 95% of the rocks on Earth. This module covers the structure of silicates, the most common minerals in the Earth's crust. The module explains the significance of the silica tetrahedron and describes the variety of shapes it takes. X-ray diffraction is discussed in relation to understanding the atomic structure of minerals.
Silica is silicon dioxide, the most common component found in rocks and minerals. The composition of different types of magmas are assessed partly based on silica content, or the amount of silica in them.