AUTOMETAMORPHISM

Autometamorphism

AUTOMETAMORPHISM (from the Greek words "autos", which means "self", and "metamorphoomai", which means "am transformed", "am transforming" * EN: autometamorphism; DE: Autometamorphose; FR: autometamorphisme; ES: autometamorfismo; RU: автометаморфизм) is the combination of the physical and chemical processes, which cause the change of the mineral composition of the rocks under the influence of the solutions and fluids, which are genetically related to the forming rocks. There may occur during this process both the recrystallization of the minerals, and their metasomatic transformation.

Several researchers believe, that the processes of the autometamorphism start yet at the magmatic stage, and according to this belief, they distinguish the properly magmatic (temperature more than 600 degrees Celsius), pneumatolytic (temperature 600-375 degrees Celsius), and hydrothermal (temperature less than 375 degrees Celsius) stages.

According to the ideas, which are developed by the soviet scientist D.S.Korzhinsky, the processes of the autometamorphism are related only to the post-magmatic stage, during which the rock, which is already hard, undergoes the transformation. The processes of the transformation of the minerals in the presence of the magma under the influence of the transmagmatic solutions belong to the metamagmatism. In this case (for example, for the granitoids) they distinguish the stages of the acidic leaching and of the precipitation of the bases.

The saussuritization (albitization) of the plagioclase, the chloritization of the amphibole, the spilitization and uralitization of the rocks of the base composition, the propylitization of the base and intermediate rocks, the greisenization of the leucogranites, etc., are the examples of the autometamorphism.