Abstract

CARUGNO DURAN, Andrés  and  ORTIZ SUAREZ, Ariel. The low-pressure metamorphic sequence in the Sierra de Socoscora, San Luis, and their regional implications. Rev. Asoc. Geol. Argent. [online]. 2012, vol.69, n.2, pp.187-194. ISSN 0004-4822.

The low-pressure high-temperature metamorphic sequence recognized in the Sierra de Socoscora is formed by schists with cordierite and andalusite porphyroblasts, schists with sericite nodules, muscovitic-biotite-quartz schists and amphibolites, in tectonic contact with migmatites and granitoids. The outcrops of this sequence are discontinuous, ranging from a few meters to several square kilometers; in some cases occur as xenoliths within the granitoids. This metasedimentary sequence which is inter-bedded with metabasites provides evidence of at least three deformational phases (F1, F2 y F3) together with a low pressure metamorphic evolution. F1 is developed jointly with a M1 metamorphism (Bt1 + Ms1), static cordierite grows subsequently between the F1 and F2 phases resulting in M2 (Crd + Bt2 + Qtz + Kfs), the thermal climax is reached during the F2 phase with the presence of sillimanite (fibrolite), giving way to M3 (Bt3 + Ms2 + Sil). Subsequently, the growth of static andalusite post F2 generates M4 (And + Ms3). Finally, F3 produced crenulation cleavage (S3). The abundance of mafic rocks and/or granitoids in the zone could be responsible for the high gradients which allowed for the development of the characterized paragenesis. In other sectors of the Sierras Pampeanas, rocks formed under similar conditions have been reported, associated with processes assigned to the Pampean and Famatinian orogenies. The lack of geochronological data hinders the accurate assignment to a particular stage. The rocks described in this work could correspond to shallower levels than those representing the migmatites in the region.

Keywords : High-temperature - low-pressure metamorphism; Famatinian and Pampean orogenies.

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