Geodynamic setting for LCT and beryl pegmatites in the NW Argentina Famatinian arc

LÓPEZ DE AZAREVICH, VANINA; AZAREVICH, MIGUEL; ANNA GIONCADA; FULIGNATI, PAOLO; M. M. ORTEGA PÉREZ

Puerto Madryn

Congreso; XXI Congreso Geológico Argentino; 2022

Asociación Geológica Argentina

The Famatinian geologic configuration of NW Argentina was a convergent margin in which developed a volcanic arc, a back-arc and a foreland basin. These allocate different ore deposits belonging to Metallogenic Epoch II defined by López de Azarevich and Azarevich (2020): Orogenic epithermal gold in Sierra de Rinconada; Polimetallic vein deposits along Eastern Cordillera; Rare elements’ pegmatites in El Quemado District and Luracatao area; VMS in Sierra de Calalaste and La Colorada-Limeca District; Sedex in Aguilar-Esperanza District; Phosphate rocks in Eastern Cordillera.The arc setting extends from the Bolivia-Argentina boundary up to ~26°S. It integrated paired arcs in Puna region that conforms the Western and Eastern Puna Eruptive Belts, and crustal-derived intrusives farther SE in North-Western Pampean Range. The first ones are emplaced in the Arequipa-Antofalla (A-A) crustal block and the second in the Pampean block (Figure 1).The geodynamics of A-A, which was built-up of various blocks accreted prior to 1 Ga (Rapela et al., 2007), conditioned the evolution not only of the magmatic arcs and metamorphic belts until the Middle Paleozoic, but also of the marine basins’ configuration and closure. From its amalgamation, it served as an autochthonous pericontinental terrain or block that suffered drifts and polycyclic accretions; ending its re-approachment and final accretion history in the Silurian.The Famatinian pegmatites ore bodies outcrop in the northern part of the Western Pampean Range, and belong to the Pampean Pegmatite Province (Galliski, 2009), with the main examples in the Sierra de Cachi (El Quemado District) and Cordón de Luracatao (Patricia, Olga and Lorena Mines). The chemical composition of pegmatites differs from Li-rich to the east to Be-rich to the west, respectively.