Orogenezis

Orogenezis, also called orogeny, is the geologic process by which mountain belts are formed through long-term deformation of the Earth's lithosphere caused by plate tectonics. It involves crustal shortening, thickening, uplift, and often associated metamorphic and magmatic activity.

Most orogenies occur at convergent plate boundaries. Continent–continent collision thickens crust, producing high mountain belts; subduction of oceanic crust beneath continental crust can generate volcanic arcs and later continental collision. Accretion of exotic terranes at margins also contributes to crustal growth and mountain building.

Structural features of orogens include folds (anticlines and synclines), thrust and reverse faults, and foliated metamorphic rocks from regional metamorphism. Magmatism is common, yielding plutonic and volcanic rocks. Erosion exposes deep crustal rocks and contributes to topographic relief.

Historically recognized orogenic episodes include the Variscan (Hercynian), Caledonian, and Alpine cycles in Europe, the Cordilleran orogenies in the Americas, and the Himalayan–Tibetan orogeny in Asia. These events occurred over tens to hundreds of millions of years and often recur as plate motions reorganize.

Orogenezis is distinguished from epeirogeny, vertical movements that do not create major mountain belts. Studying orogenesis helps explain the distribution of metamorphic and igneous rocks, the architecture of continents, and the evolution of Earth's topography.