GEODYNAMIC SETTING FOR LCT AND BERYL PEGMATITES IN THE NW ARGENTINA FAMATINIAN ARC

LÓPEZ DE AZAREVICH, VANINA; AZAREVICH, MIGUEL; GIONCADA, ANA; FULINGATI, PAOLO; ORTEGA PÉREZ, MARÍA DE LAS MERCEDES

Chubut

Congreso; XXI Congreso Geológico Argentino; 2022

In Sierra de Cachi two bi-modal magmatic suites of the Cachi Formation are outcroping: i) TT (trondhjemitic), I-type, conformed by gabbros, diorites, tonalites and trondhjemites, dated in 477.5 ± 3.9 Ma; ii) Calc-alkaline, S-type, involving granodiorites, peraluminous granites and pegmatites, dated in 472.1 ± 11 Ma (Galliski et al., 1990; Hongn and Seggiaro, 2001; Hongn et al., 2014). The magmatic association resembles a transtensive tectonic in a continental island-arc, which implies subduction below the Luracatao block (Coira et al., 1999; Miller et al., 2019). Pegmatites of the LCT (Li, Cs, Ta) family, rare elements class are 4 to 30 m wide bodies emplaced in La Paya Formation (cordierite schists, peak metamorphic ~510 Ma) in El Quemado District. The following types and sub-types were recognized: i)Beryl type, beryl-columbite-phosphate subtype; ii)Complex type, petalite subtype; iii)Complex type, spodumene subtype.