Kontaktmetamorfózis

Kontaktmetamorfózis, also known as contact metamorphism, is a type of metamorphism that occurs when rock is altered by heat and chemical reactions from an igneous intrusion. This process happens when magma or lava comes into close proximity with pre-existing rock, known as the country rock. The intense heat emanating from the molten material causes changes in the mineralogy and texture of the surrounding rock without significant pressure.

The zone affected by contact metamorphism is called a metamorphic aureole or contact aureole. The size and intensity of this aureole depend on the size of the igneous body, its temperature, and the type of country rock. Fine-grained rocks, like basalt, tend to recrystallize and form coarser textures, such as hornfels. In some cases, new minerals are formed that are stable at higher temperatures.

Common minerals formed during contact metamorphism include wollastonite, garnet, cordierite, and scapolite. The original sedimentary or igneous structures of the country rock are often obliterated and replaced by a dense, interlocking mosaic of new minerals. This contrasts with regional metamorphism, which is driven by both heat and immense pressure over large areas. Contact metamorphism is a localized phenomenon, typically found around plutons, dikes, and sills.