Djupbergarter

Djupbergarter, in Swedish geology, refers to plutonic igneous rocks that crystallized at depth beneath the Earth’s surface. They form by the slow cooling of magma at depths of kilometers to tens of kilometers, producing a coarse-grained, phaneritic texture in which the mineral crystals are clearly visible to the unaided eye.

Common rock types in the djupbergarter group include granites, granodiorites, diorites, and diabases. The composition ranges from felsic to intermediate for granitic varieties (granite, granodiorite) to mafic for dioritic and gabbroic equivalents. Ultramafic rocks such as peridotite also occur within the broader classification of deep-seated rocks. Classification is typically based on mineral content, especially quartz and light-colored feldspars versus dark mafic minerals.

These rocks form large underground bodies such as plutons, batholiths, and stocks, as well as smaller intrusions like sills and dikes. They crystallize when magma stalls and cools within crustal rocks, varying in size from meters to hundreds of kilometers across in the case of batholiths.

Over geological time, uplift and erosion may expose djupbergarter at the surface. Weathering and regional metamorphism can overprint them, producing metamorphic rocks such as gneiss or migmatite in some settings.

Economically, deep-seated rocks commonly serve as sources of granite and feldspar and may host various ore deposits. They are a major component of the continental crust and provide insight into crustal formation and tectonics.