Resumo

VARELA, Ricardo et al. Isótopos de estroncio en calcáreos del noreste Patagónico: resultados preliminares. Rev. Asoc. Geol. Argent. [online]. 2014, vol.71, n.4, pp.526-536. ISSN 0004-4822.

We have carried out measurements of strontium isotopic compositions of carbonate units from northeastern Patagonia. The rock units included in the study are: a) Pailemán marble, with questionable belonging to El Jagüelito Formation, and mean ⁸⁷Sr/⁸⁶Sr value of 0.707354 ± 0.000113; b) marbles from estancia La Auriciana, Mina Gonzalito Complex, with mean ⁸⁷Sr/86Sr value of 0.708730 ± 0.000285; c) archaeocyathan limestone clasts from a metaconglomerate layer of El Jagüelito Formation in the Sierra Grande area, with mean 87Sr/⁸⁶Sr value of 0.710605 ± 0.000118. Comparison of these data with the global ⁸⁷Sr/⁸⁶Sr evolution curve suggests that the Pailemán marble is the oldest (ca. 625 Ma), followed by the estancia La Auriciana marbles (ca. 550-510 Ma), while the archeocyathan limestone clasts from Sierra Grande area are Cambrian.

Palavras-chave : El Jagüelito Formation; Mina Gonzalito Formation; Chemostratigraphy; ⁸⁷Sr/⁸⁶Sr.

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