Resumo

BAEZ, Walter; ASTINI, Ricardo; EZPELETA, Miguel  e  MARTINA, Federico. Facies volcaniclásticas y paleoambiente sedimentario de la formación Punta del agua, carbonífero temprano de la precordillera septentrional, La rioja. Rev. Asoc. Geol. Argent. [online]. 2014, vol.71, n.2, pp.210-232. ISSN 0004-4822.

The Punta del Agua Formation (Lower Carboniferous) crops out in the northern Precordillera de Jagüé, La Rioja province, within the western domain of the Paganzo basin. It is a volcano-sedimentary succession of about ~ 1600 m thick, consisting of volcanic and subvolcanic rocks of variable composition between felsic and basic ends, with breccias, conglomerates, sandstones and shales. In this contribution we present a reference stratigraphic section for The Punta del Agua Formation and a facial analysis of the unit. The basin fill is characterized by the development of fan-delta systems with local volcanic sources represented by lava flows and subvolcanic dykes which could be conduits feeders of the effusive facies. In proximal areas deposition was dominated by hyperconcentrated and concentrated flows. On the other hand, the prodelta facies were dominated by more diluted turbiditic flows with evidences of glacial influence. The interdigitated yellow epiclastic conglomerates and sandy materials recorded at the base of the section which were informally grouped as the Amarillo Member. This latter represents braided rivers systems with sources outside the basin located to the E of the study area. The analysis of the complex internal architecture and stratigraphic relationships of the unit allow characterizing the paleoenvironment and suggesting alternatives for its tectonic setting.

Palavras-chave : Paganzo basin; Missisipian volcanism; Volcano-sedimentary succession; Facies analysis.

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