andesiittinen
Andesiittinen is a Finnish term used in geology to describe rocks, magmas, and volcanic activity with an intermediate silica content, between basaltic and rhyolitic compositions. In technical usage, andesitic rocks typically contain about 57–63 percent SiO2, though exact boundaries can vary among sources. The adjective andesiittinen applies to both the rocks themselves (andesite) and the magmas that crystallize to form them.
Formation and occurrence: Andesitic magmas mainly form in subduction-zone settings. Fluids released from the subducting oceanic
Petrology and textures: Common minerals in andesitic rocks include plagioclase (often calcium-rich) together with pyroxene and/or
Geological significance: Andesitic volcanism characterizes many convergent plate boundaries and is associated with major volcanic arcs,
Notes: The label andesiittinen is descriptive of composition; precise chemical boundaries vary, and some rocks near