Anatectic granites of the Sierras Pampeanas from Córdoba (Argentina): U-Pb SHRIMP and zircon trace element LA-ICP-MS study of diachronic metamorphism and crystallization

D'ERAMO, FERNANDO JAVIER; CONIGLIO, JORGE; ESTEBAN, J.J.; ARAGÓN EUGENIO; DEMARTIS, MANUEL; PINOTTI, LUCIO

GEOGACETA

Sociedad Geológica de España

Lugar: Barcelona; Año: 2020 vol. 68 p. 95 - 98

0213-683X

In this contribution we present new U-Pb SHRIMP ages and insitu LA-ICP-MS trace element geochemistry of zircon crystals fromthe Río de los Sauces anatectic granite, Córdoba, Argentina. Notabledifference in texture and composition allowed us to identify twozircon populations in a single granite sample that are interpretedas reflecting metamorphic and igneous origins. Zircons regardedas restitic crystals entrained during the melt segregation yielded aslightly older concordia age of 537.1 ± 4.8 Ma (2σ) than those interpretedas igneous, dated at 529 ± 6 (2σ) Ma. Inherited metamorphiczircons are interpreted to represent solid-state growth during hightemperature metamorphism of the Pampean Orogeny at the onsetof the anatexis or metamorphic peak. Meanwhile, igneous zirconswould record the crystallization age of Zr within the Río de los Saucesgranite. The textural, compositional and geochronological data ofboth zircon populations suggest that the inception of the anatexis,the melt segregation and crystallization occurred during a short periodof time of 8 my.