Complejo Los Menucos: un evento volcánico permo-triásico en el norte de Patagonia

LUPPO, TOMÁS; LÓPEZ DE LUCHI, MÓNICA G.; MARTÍNEZ DOPICO, CARMEN; RAPALINI, AUGUSTO E.; FANNING, C. MARK

San Miguel de Tucumán

Congreso; XX Congreso Geológico Argentino; 2017

Asociación Geológica Argentina

Three new U?Pb SHRIMP ages on zircon are presented for volcanic units of Los Menucos Complex, located in extra andean northern Patagonia. An around 6 km thick composite geologic section, made up by rhyolitic and dacitic ignimbrites, mesosilisic lavas and subordinated volcaniclastic-epiclastic deposits is presented. The obtained ages are: 256.8 ± 1.7 Ma for a rhyolitic ignimbrite, 252.4 ± 1.8 Ma for an andesite and 248.3 ± 1.6 Ma for a dacitic ignimbrite. These crystallization ages that correspond respectively to the basal, middle and upper portions of the section, constrain the main activity of the Complex to a 10Ma period across the Permian-Triassic boundary. The La Esperanza Magmatic Province is proposed as a new major unit that encompass Los Menucos Complex and La Esperanza Plutono-Volcanic Complex, because the complexes are coeval, nearby and no crustal discontinuity is recognized between them.