Lamprófiros Shoshoníticos (Minettes) del Noreste de la Sierra de San Luis.

LÓPEZ DE LUCHI, MÓNICA G.; MARTINEZ DOPICO, CARMEN; MONTENEGRO, T.

Córdoba

Congreso; Congreso de Mineralogía, Petrología Ígnea y Metamórfica, y Metalogénesis: XIII MINMET y IV PIMMA; 2019

Asociación Geológica Argentina

Mica lamprophyres, identified as minette occur mainly as dykes that crosscut the pegmatites and basement rocks of Conlara Metamorphic Complex and occasionally as enclaves. Lamprophyric rocks are formed by the early magmatic paragenesis phlogopite-apatite that appear as phenocrysts; feldspars are found in the groundmass. The chemical evolution of the pholopite is consistent with increasing oxygen fugacity during late magmatic stages. Whole-rock geochemical data suggest a metaluminous, ultrapotassic parental liquid, with silica saturation close to the limit of undersaturation. Trace element concentrations, such as enrichment in large ion lithophile and strong depletion of some high-field strength elements, indicate a mantle source that was partially modified by crustal components in a subduction setting. The strong enrichment of light rare-earth elements is characteristic and allows to connect them with the Monzonites Series of Devonian magmatism of the Sierra de San Luis.