La Tectónica Extensional y el Magmatismo bimodal calcoalcalino-alcalino Paleogeno en el tramo de Patagonia Septentrional (38ºS a 44ºS)

ARAGON, E; CAVAROZZI, C.E.; AGUILERA, Y.E.; RIBOT A.

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 2008

0004-4822

Continental crust heterogeneities at active continental margins may play an important role in the development of regional extensional features and related volcanism. This paper considers such case. Very low convergence ocean-contienental plate angle and wide spread calcalkalic-alkalic bimodal volcanism at an extensional tectonic setting occurs at Eocene-Oligocene-early Miocene in Septentrional Patagonia. This unusual tectonic setting is related to a Transform type active margin where an undeformable epeirogenic block very close to the continental margin interacts with the thin deformable continental crust (orogenic belt). Along with extension is the uplift of the epeirogenic block. Extensional areas are caused by the rotation of the coast blocks with respect the central epeirogenic block. At the far end of the extensional areas, extension is so great, that alkali basalts with mantle xenoliths occur at the same time with large calcalkalic volcanism along the same fault systems and time.