Resumo

LAJOINIE, María F; LANFRANCHINI, Mabel E; ETCHEVERRY, Ricardo O  e  RECIO, Clemente. Zonación mineral vinculada a procesos geoquímicos en el skarn San Miguel, sierras septentrionales de la provincia de Buenos Aires. Rev. Asoc. Geol. Argent. [online]. 2013, vol.70, n.3, pp.380-400. ISSN 0004-4822.

The San Miguel skarn represents an unusual geological event in the Septentrionales ranges in the Buenos Aires Province. It is developed on a coarse-grained calcite marble that crops out sparsely in the region. The skarn was form in response to the intrusion of a tonalitic composition magma that surrounded the marble which was partly assimilated, leaving relict cores. The skarn shows a zoned pattern, with (1) wollastonite-vesuvianite, (2) garnet-clinopyroxene, (3) clinopyroxene zones in an exoskarn and (1) garnet-clinopyroxene, (2) Ca plagioclase-clinopyroxene zones in an endoskarn. Stable C and O isotopic ratios suggest a carbonate of marine origin, whose original isotopic signature had later been modified by metamorphism and metasomatism. The detailed analysis of mineral zoning has genetic implications that contribute to unraveling the complex evolution history of this skarn deposit.

Palavras-chave : Sierras Septentrionales; San Miguel skarn; Proterozoic basament; Buenos Aires.

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