Resumo

MOROSINI, Augusto; ORTIZSUAREZ, Ariel  e  RAMOS, Gabriel. TheFamatinian granitoids of the southwestern sector of Sierra de San Luis: Classification and geothermometry. Rev. Asoc. Geol. Argent. [online]. 2009, vol.64, n.3, pp.433-446. ISSN 0004-4822.

Several plutons belonging to an old magmatic arc arerecognized in the southwestern of the Sierra de San Luis. They are emplaced inmetamorphic rocks of greenschist to lower amphibolites facies, and interpretedas pre-ocloyic, older than 460 Ma, within the Famatinian orogenic cycle. Themapping, petrographic study, and chemical microanalysis in feldspars, haveenabled a classification of the plutonics roks of the area and have revealedpart of the history of cooling and emplacement of the different facies. Also,the chemical microanalysis in feldspars shows that there is great variation inthe An content of plagioclase in the mafic series, in comparison with those ofthe felsic series, indicating a variation in the range of temperatures from1100° to 748° C respectively, and a probably different origin of magmas. Thedata were modeled and adjusted to existing theoretical diagrams of isothermsfor the system or-ab-an, and for an internal pressure of H₂O 5000bars (pseudo-isobaric system).

Palavras-chave : Basement; Plutonic rocks; Plagioclases; Microanalysis; Temperatures.

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