The Gondwana connections of northern Patagonia

PANKHURST, B; RAPELA, C.W.; LÓPEZ DE LUCHI, M. G.,; RAPALINI, A.E.; FANNING, C.; GALINDO, C.

Viña del Mar

Congreso; INTERNATIONAL GEOLOGICAL CONGRESS ON THE SOUTHERN HEMISPHERE; 2013

Universidad Andrés Bello

A multidisciplinary study (U-Pb SHRIMP geochronology, Hf and O isotopes in zircon, Sr and Nd isotopes in whole-rocks, as well as major and trace element geochemistry) has been carried out on granitoid samples from the area west of Valcheta, North Patagonian Massif, Argentina. These confirm the Cambrian age of the TardugnoGranodiorite (528 ± 4 Ma) and the Late Permian age of granites in the central part of the Yaminué complex (250 Ma). Together with petrological and structural information for the area, we consider the possibility that the Cambrian and Ordovician granites of northeastern Patagonia represent continuation of the Pampean and Famatinian orogenic belts of the Sierras Pampeanas, respectively. Our interpretation does not support the hypothesis that Patagonia was accreted in Late Palaeozoictimes as a far-travelled terrane, originating in the Central Transantarctic Mountains, and the arguments for and against this idea are reviewed. A parautochthonous origin is preferred with no major ocean closure between the North Patagonian Massif and the Sierra de la Ventanafold belt.