Cooling and Nd model ages of the Devonian to Late Paleozoic units of the SW corner of the North Patagonian Massif

LÓPEZ DE LUCHI, M.G., CERREDO, M.E., WEMMER, K., PAWLING, S

La Plata

Congreso; 16 Congreso Geologico Argentino; 2005

Asociación Geologica Argentina, INREMI

Geochronological, petrological and structural evidences suggest that along the western border of the MNP Devonian metamorphism may have followed an Ordovician(?)-Early Devonian active margin active margin stage that evolves to its closure (crustal thickening and D2 deformation) during Middle to Late Devonian times. Late Paleozoic (ca. 300 Ma) magmatism developed during D3 in a contractional setting (Cerredo 1997, Ostera et al, 2001). This deformation was active before 278Ma, the crystallization age of the undeformed granites, and controlled an stage of uplift of the basement complex, as evidenced by decompression trajectories in CF and the epizonal emplacement of the Early Permian granitoids. Cooling of the basement below 300 º C occurred during the Late-Permian-Middle Triassic. Mesoproterozoic sources are envisaged for the protoliths of the Cushamen Formation whereas younger TDM the Mamil Choique granitoids could indicate either a different crustal segment or mixed sources.