Original paper

Provenance and geotectonic setting of Late Proterozoic Early Cambrian metasediments in the Sierras de Cordoba and Guasayan (western Argentina): a geochemical approach

von Gosen, Werner; Buggisch, Werner; Prozzi, César

Abstract

Geochemical analyses from Late Proterozoic - Early Cambrian clastic metasediments of the Sierras Norte de Córdoba, Sierras Grandes de Córdoba and Sierra de Guasayán (western Argentina) show a wide spread from arkoses over litharenites and wackes to shales, and partly greywackes. Discriminant function diagrams suggest a felsic igneous and quartzose sedimentary provenance for the sediments of the Lower and Upper Unit in the Sierras Norte de Córdoba, respectively, and a quartzose provenance for those in both other areas. The analyses record a weak weathering suggesting short sedimentary transports. Major element diagrams suggest passive and partly active continental margins for the Sierras Norte and an active continental margin with an overlap to the passive margin for the Sierras Grandes de Córdoba/Guasayán. The trace element diagrams do not indicate a setting of the Upper Unit samples in an active margin. They show that the Lower Unit was dominated by recycling of acidic continental crustal material whereas the other sediments point to the influence of old sediment components. Also, in view of the rare earth element diagrams, a setting of the Lower and Upper Unit on a passive margin is probable. With its clastic content derived from local clastic and magmatic rocks, the Lower Unit probably was covered by the Upper Unit deposited in a shelf area that received clastic and magmatic detritus also from a hinterland in the east. Sedimentary transports into a wide Puncoviscana basin in the west are according to the situation in northwest Argentina and have an equivalent in the Antarctic area of the later-formed Ross orogen. This suggests a comparable passive margin development at the paleo-Pacific side of Gondwana in the South American (Pampean) and Transantarctic (Ross) sectors, with sedimentary transports from inner Gondwanan cratonic areas during the Late Proterozoic - Early Cambrian times.

Keywords

gondwanasierras pampeanasgeochemistrysedimentationprovenance