Abstract

DALLA SALDA, L.H.; ARAGON, E.; BENIALGO, A.  and  PEZZOTTI, C.. A calcareous platform on the Mina Gonzalito Complex, Río Negro Province. Rev. Asoc. Geol. Argent. [online]. 2003, vol.58, n.2, pp.209-217. ISSN 0004-4822.

A succession of garnet zone calcitic and dolomitic marbles cropping out to the south of the Mina Gonzalito Complex, near the Río Salado represent part of a carbonate bank developed during a trangressive episode of a continental rifting. The marbles occur in a complex antiformal interference structure. At the top of the section, two dolomitic marbles are conspicuous. Their geochemistry shows an increase in MnO and MgO towards the base of the sequence. The upper part of the section shows a low Na₂O content whereas the lower part is Na₂O rich. Dolomitic marbles have a higher SiO₂, Ti and Ba content and SiO₂/Al₂O₃ relation than calcitic ones. The conformable attitude of the marbles with the Mina Gonzalito Complex indicates that they were part of the near-shore platform with deeper-water rocks to the north, in turn related to volcanism associated with Gonzalito mineralization. The Lower Palaeozoic regional metamorphic event that affected the marbles modified the composition of the protolith very little.

Keywords : Marbles; Mina Gonzalito Complex; Rifting; Cambrian; Eastern Northpatagonian Massif.

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