Vaihemuunnos

Vaihemuunnos, also known as intermediate metamorphism, is a geological process that occurs between the low-grade metamorphism of diagenesis and the high-grade metamorphism of regional metamorphism. It is characterized by the transformation of rocks under moderate temperatures and pressures, typically ranging from 200 to 400 degrees Celsius and 1 to 5 kilobars, respectively. This process often occurs in the roots of mountain belts, where tectonic forces cause rocks to be buried and heated.

During vaihemuunnos, rocks undergo changes in their mineralogy and texture. Common minerals that form during this process include chlorite, biotite, and garnet, which are stable under the moderate conditions of intermediate metamorphism. The resulting rocks are typically foliated, with a preferred orientation of minerals that reflects the direction of stress during metamorphism.

Vaihemuunnos is an important stage in the geological history of many mountain belts, as it can significantly alter the properties of rocks and influence their subsequent behavior during further deformation and metamorphism. The study of intermediate metamorphism provides valuable insights into the tectonic processes that shape the Earth's crust and the evolution of mountain belts over time.