Mathematical Modeling of Overthrusting Fault as a Cause of Andalusite-Kyanite Metamorphic Zoning in the Yenisei Ridge

摘要

Regional structural features of the Yenisei Ridge are traditionally displayed as a NW-trending linear system of tectonic sheets that are thrust over one another and separated by faults where collision of blocks occurs (Fig. 1). As a result, low- and moderate-pressure series of regional metamorphism turn out to be juxtaposed. Moderate-pressure metamorphism related to collision is locally superimposed on low-pressure metamorphic rocks. Therefore, andalusite is progressively replaced with kyanite, and new mineral assemblages of moderate pressure and deformational microstructures are formed. The replacement of andalusite by kyanite in the Yenisei Ridge is not a common phenomenon, because the stationary continental geotherm, as a rule, does not intersect the andalusite-kyanite equilibrium line.