Abstract

MOROSINI, Augusto  and  ORTIZ SUAREZ, Ariel. The Famatinian deformation of  La Escalerilla Granite, Sierra de San Luis. Rev. Asoc. Geol. Argent. [online]. 2010, vol.67, n.4, pp.481-493. ISSN 0004-4822.

In this paper post-magmatic structures of  La Escalerilla Granite are analyzed and an interpretation of  regional deformation mechanisms is proposed for cycle Famatinian of  the Southwestern sector of  the Sierra de San Luis. It is thought that La Escalerilla pluton has conditioned the style of  deformation of  the lithologic units at its periphery. This deformation was linked to the rheological contrast which occurred between the intrusive and metamorphic country rocks. The structure of  the pluton is characterized by the presence of: a) an internal foliation of  submeridianal orientation particularly marked in the border sectors, as well as to the north and south of  the body; b) a NNE-trending mylonitic belt in the eastern contact; c) conjugated shears of  synthetic Riedel (NNW) and antithetic Riedel (NE) types, interpreted as part of  an tectonic escape under a sinestral transpressive regime; and d) tensional fractures of  WNW orientation. All these structures are thought to correspond to the compression in the WNW-ESE direction, generating a real component of  tangential sinestral stress, of  variable module, because of  the pluton general obliquity with relation  the axis of  maximum stress  (σ1). However,  in some sectors  this  tangential component  is minimal due  to  the different orientations of  the boundaries of  the body with respect to the vector of  maximum stress (σ1).

Keywords : Structure; Ductile; Rheology; Tectonic escape; Sierras Pampeanas.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )