Lamprofíros Shoshoníticos (Minettes) del Noreste de la Sierra de San Luis

MARTINEZ DOPICO, C.I.; MARTINEZ DOPICO, C.I.; LÓPEZ DE LUCHI, M. G.; LÓPEZ DE LUCHI, M. G.; MONTENEGRO, T.; MONTENEGRO, T.

Cordoba

Congreso; XIII Congreso de Mineralogía, Petrología Ígnea y Metamórfica, y Metalogénesis; 2019

Asociacion Geologica Argentina

ABSTRACT:SHOSHONITE LAMPROPHYRES (MINETTES) OF NORTHEASTERNSIERRA DE SAN LUIS. Mica lamprophyres, identified as minette occur mainly as dykes thatcrosscut the pegmatites and basement rocks of Conlara Metamorphic Complex and occasionallyas enclaves. Lamprophyricrocks are formed by the early magmatic paragenesis phlogopite-apatitethat appear as phenocrysts; feldspars are found in thegroundmass. The chemical evolution of the phlogopite is consistent with increasing oxygen fugacity during late magmaticstages. Whole-rock geochemical data suggest a metaluminous, ultrapotassic parental liquid, with silica saturation close to the limitof undersaturation. Trace element concentrations, such as enrichment in large ionlithophile and strong depletion of some high-fieldstrengthelements, 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.