The 1800 Ma mylonite-anatectic granitoid association in Tandilia, Argentina

Abstract

The mylonitic belts, developed on metamorphic and migmatic rocks, trend preferentially E-W, although some of them strike SW-NE. Nearly 40 km wide mylonites, blastomylonites and cataclasites were developed in the Azul area, in a transcurrent system which, as in other mylonitic belts, also produced low angle thrusting, secondary fold systems, and related basic intrusive rocks. Major and trace element analyses have shown that most of the associated granitoids are of anatectic origin related to the thickening of a continental border. This border was created during a period of collision with a newly attached southern Gondwana continent, which now forms most of Patagonia, south of Tandilia. -from Authors