Nuevas evidencias acerca de la presencia de una banda de cizallamiento en la secuencia metapelitica de la Formación Silgará, sector Aratoca-Pescadero (region suroccidental del Macizo de Santander)

Abstract

The metamorphic sequence of the Silgara Formation that crops out in Pescadero-Aratoca area (southwestern region of the Santander Massif), presents evidences of having suffered an important shear deformation during its exhumation path, which affected great part of the metamorphic rocks from the garnet and staurolitekyanite zones. This ductile deformation of extensional character generated structures such as lineations, pressure shades, milonitization zones, isoclinal recumbent folds, rootless folds, boudins, as well as the elongation of garnet crystals and the truncation of their chemical zonation, which suggest a proccess of gravitational collapse with an East motion, that affected the Caledonian paleo-orogen. These deformational elements, along with the evidences of an important circulation of hydrothermal fluids, make this region of the Santander Massif an important place to pay attention to explore mesotermal deposits, especially for its favorable conditions for the removization of gold.