Abstract

IANNIZZOTTO, Noelia F  and  LOPEZ DE LUCHI, Mónica G. Composition of biotites and amphiboles from the Las Chacras - Potrerillos batholith: Geochemical implications for the mid-devonian mafmatism of the Sierra de San Luis. Ser. correl. geol. [online]. 2012, vol.28, n.2, pp.39-52. ISSN 1666-9479.

The Las Chacras - Potrerillos Batholith is the largest Devonian igneous unit that crops out in Sierra de San Luis. According to its silica content it is divided into two suites: Monzonitic ( 65% SiO2). New mineral chemical data obtained by electronic microprobe on biotites and amphiboles of both suites are presented. The analysis of biotite composition indicates that Mg/(Mg + Fe) is higher for the Monzonitic Suites and the calc-alkaline, metaluminous to peraluminous magmatic signature. Emplacement pressure calculated from the amphibole data are bracketed between 3,3 - 4,6 Kbar (Monzonitic Suite) and 4,2 - 4,7 Kbar (Granitic Suite).

Keywords : Magmatism; Devonian; Biotite; Amphibole.

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