Geochemistry and provenance of pre-late Cretaceous Units in Argentine Tierra del Fuego: Preliminary results

CERREDO, M. E.; REMESAL, M. B.; TASSONE, A.

Antofagasta, Chile

Congreso; XI Congreso Geológico Chileno; 2006

Universidad de Chile

The pre-Late Cretaceous units of Argentine Tierra del Fuego are represented by the restricted outcrops of the Basement Complex (BC), the Upper Jurassic siliceous volcanic/volcaniclastic Lemaire Formation (LF) and two Lower Cretaceous sedimentary units: Yahgan (YF) and Beauvoir Formations. These last three units form NW-SE belts which cut across the Isla Grande de Tierra del Fuego (Fig. 1). The BC (made up of very low- to low-grade metamorphic rocks in Argentina) was interpreted as the Late Paleozoic to Early Mesozoic accretionary wedge formed along the western Panthalassic margin of Gondwanaland later metamorphosed and uplifted prior to the Late Jurassic (Dalziel 1982). LF comprises the acid volcanic and interlayered volcaniclastic rocks evolved in the extensional tectonic regime which led to the formation of the Rocas Verdes back-arc Basin (RVB). The Lower Cretaceous units represent the infilling of the RVB with detritus source areas located either in the Southern magmatic arc -YF- or in the northern margin of the basin –Beauvoir Fm.- (Olivero and Martinioni, 2001).