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Clara Eugenia Cisterna, CONICET -Universidad Nacional de Tucuman (Argentina)
Ricardo Mon, CONICET -Universidad Nacional de Tucuman (Argentina)
Rodolfo Mena, Universidad Nacional de Tucuman (Argentina)
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The Las Cañas (LCC) Complex represents a portion of the metamorphic mid-crustal basement migmatitic belt in the sierra de Aconquija (Sierras Pampeanas Septentrionales, NW Argentina). A complete range from folded metatexite to diatexite migmatites has been produced during a high-grade metamorphic and deformational event. The structural study reveals a shear episode at the end of the migmatization. New field, fabric and mineralogical observations allow constraining pre-, syn-and post-migmatitic deformational phases. It is argued that migmatitic rocks and minor anatectic leucogranites were developed during a ductile folding episode and shear structures are related to later phases. Late post-migmatitic ductile-brittle deformation is evidenced by the development of a NNW-SSE striking vertical spaced crenulation cleavage. The relationships between a large diversity of migmatitic structures and the progressive production of melt suggest that feedback relations prevailed as a time-marker during a contractional regime. Deformation, metamorphism, and plutonism of the LCC show that this terrane evolved as a verging thrust system with synkinematic metamorphism and partial melting during the Late Proterozoic - Early Paleozoic. The tectonic history and lithologies of LCC are compared to the sierra de Ancasti (La Majada Complex, southern to the studied area), showing that they belong to a same regional belt within the Catamarca portion of the Pampean Ranges, northwestern Argentina.
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