Mylonitization is a geological term that refers to the process of rock deformation under high pressure and temperature. It is spelled as /maɪləˌnaɪtɪˈzeɪʃən/ where the first syllable is pronounced with a long "i" sound /[aɪ]/, and the second syllable with a schwa sound /ə/. The third syllable is pronounced with a long "i" sound /aɪ/ followed by the consonant group "tɪ", and the last syllable is pronounced with a "sh" sound /[ʃən]/.
Mylonitization is a geological process that involves the transformation and deformation of rocks due to intense mechanical stress resulting from tectonic forces. It occurs in regions of high strain, typically along fault zones or shear zones. The process is characterized by the gradual breaking and comminution of minerals, primarily through fracturing and pulverization, leading to the formation of a rock type known as mylonite.
During mylonitization, the original rock becomes highly deformed, resulting in a distinct foliated texture marked by closely spaced parallel planes, known as foliation, which are aligned perpendicular to the direction of the strain. This foliation represents the preferred orientation of minerals and the alignment of broken fragments within the rock.
Mylonitization commonly occurs in areas of intense crustal deformation, such as mountain building processes, where rock bodies are subjected to strong shearing forces. It is associated with ductile deformation, where rocks are subjected to high temperatures and pressures that enable them to undergo plastic flow. This process can occur in a variety of rocks, including igneous, sedimentary, and metamorphic rocks.
Mylonitization plays a crucial role in the development and evolution of geological structures, as well as in the formation of mineral resources. It can help geologists understand the kinematic history of fault zones, the behavior of rocks under extreme stress, and the mechanics of tectonic processes.
The word "mylonitization" is derived from the geological term "mylonite". The term "mylonite" originated from the Greek word "mylōn" which means "mill" or "grinder". The suffix "-ite" is often added to mineral or rock names, indicating that it is a specific type or variation of that mineral or rock. In the context of geology, mylonite refers to a fine-grained, foliated rock that has undergone intense mechanical deformation along a fault zone or shear zone. The process of forming or being altered into mylonite is termed "mylonitization".