Abstract

TUNIK, M.A.; VIETTO, M.E.; SCIUTTO, J.C.  and  ESTRADA, E.. Provenance of the Chubut Group Sandstones in the central area of the Sierra de San Bernardo. Preliminary analysis. Rev. Asoc. Geol. Argent. [online]. 2004, vol.59, n.4, pp.601-606. ISSN 0004-4822.

Petrographic studies were performed in order to characterize the detrital modes of the Chubut Group sandstones. Matasiete, Castillo and Bajo Barreal Formation showed distinctive petrographic characteristics. The presence of shards on the Castillo and Bajo Barreal Formations suggests that the deposition took place on an active volcanic setting. The detrital modes indicates derivation from three different environments among the Chubut Group. The Matasiete Formation shows a provenance from a non-dissected magmatic arc. Meanwhile, the detrital modes of the Castillo and Bajo Barreal Formations suggest derivation from a transitional to dissected arc. A westward migration of the volcanic arc and the exposition of the volcanic roots of the Early Cretaceous arc by deformation in the fold and thrust belt to the west as suggested by previous works are reinforced with these results.

Keywords : Detrital modes; Provenance analyses; Arc migration; Chubut Group; Argentina.

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