Cooling ages constraints on the tectonic activity of the Los Túneles Shear Belt, Eastern Pampean Ranges of Córdoba, Argentina

MARTINO, ROBERTO DONATO; GUERESCHI, ALINA BEATRIZ; WEMMER, K.; LÓPEZ DE LUCCHI, M.; STEENKEN, A.; SIEGESMUND, S.

Punta del Este, Uruguay

Congreso; V South American Symposium on Isotope Geology (VSSAGI); 2006

Facultad de Agronomía y Facultad de Ciencias, Universidad de la República, Uruguay

In the Sierras Pampeanas of Córdoba there are sixteen ductile deformation belts whose tectonic meaning allows to assign them to four groups. One of those groups, to the one that belongs to Los Túneles Shear Belt (FDLT), they are belts of post metamorphic unroofing of the Cambrian Pampean Orogen, of inverse nature, produced by convergent general shears (transpressure), related with posthumous collisionals stages of the Pampia terrane against the margin of Gondwana and with the Famatinian subduction.  New radiometric data obtained by the K/Ar method in amphibole and mica allow to constrain the tectonic activity of the FDLT who would be been nucleated after the metamorphic peak M2 (ca. 534 Ma), unroofing the Cambrian Orogen and exhuming it until the lower Ordovician (beginning of the Famatinian subduction), when it is emplazed the Charquina granodiorite (474 Ma). The period of tectonic activity of the FDLT (ca. 64 Ma), it would coincide with the approach from the Cuyania terrane to the Gondwana margin, before its location and final collision in the upper-medium Ordovician. At the same time, in the Pampean environment the contractional final stages of the collision of the Pampia terrane with the western margin of Gondwana would be producing.  Later on, the FDLT would have cooled down until the medium Silurian, when the Sierra de Córdoba and San Luis continued its exhumation going by the thermochron of the muscovite. After this generalized cooling, the Devonian deformation and magmatism that affected pervasively to the Eastern Pampean Ranges follows.