Geochemistry of metasedimentary rocks from the Puncoviscana Complex in the Mojotoro Range, NW Argentina: Implications for provenance and tectonic setting

Low-grade metasedimentary rocks from the Lower Paleozoic Puncoviscana Complex of the Mojotoro Range in NW Argentina have been analyzed for their major and trace elements - including rare earth - in order to constrain their provenance and depositional tectonic setting. They show a moderate degree of chemical weathering with intermediate CIA (<75) values and can be classified as metawackes and metapelites. Provenance discrimination diagrams based on major element geochemistry and trace element ratios (i.e., Cr/V, Y/Ni, Th/Co, La/Sc, Th/Sc, Eu/Eu*) suggest that the sediments were derived from upper crustal, felsic source rocks. Tectonic setting discrimination diagrams based on major elements, immobile trace elements (i.e., La- Th- Sc and Th-Sc-Zr/10) and La/Yb vs. Eu/Eu* plots, support an active margin setting associated with a magmatic arc located to the east of the Neoproterozoic-Cambrian Pampean Brazilian arc that formed along the margin of a Mesoproterozoic craton.