Abstract

CHILIGUAY, José et al. PALAEOENVIRONMENTS OF THE PUNCOVISCANA FORMATION (NEOPRO-TEROZOIC-EARLY CAMBRIAN) EN THE EASTERN SECTOR OF THE LEON CREEK, JU-JUY PROVINCE.. Ser. correl. geol. [online]. 2019, vol.35, n.1, pp.1-20. ISSN 1666-9479.

The Puncoviscana Formation (Neoproterozoic-Early Cambrian), cropping out in Leon creek, Jujuy province, was recognized in four sedimentological profles with lithofacies of calca-reous conglomerates, quartzites, meta-sandstones and meta-pelites. The sequence registers fossil material of medusoids (Beltanelloides sp.), Cnidaria (Corymorpha) and trace fossils of Helminthoidichnites, Plano-lites isp., Archaeonassa isp., Palaeophycustubularis, Nereites isp., which allow to assign a marine domain and a minimum Early Cambrian (Fortunian) age. The associated sedimentary structures that define asymme-tric and linguoid ripples, through and hummocky, as well as palaeochannel architectures with imbricated clasts and fute casts, are diagnostic of shallow palaeoenvironments dominated by waves, tides and ebb tidal currents with a source of calcareous clasts from the east. The heterolithic structures (fasser, ondu-litic and lenticular) and the presence of tidal rhythmites are indication of estuaries dominated by tides, whereas the interference ripples indicate palaeoenvironments affected by interaction of tidal and litoral current’s process. The integration of facies associations suggest a shallow basin in which tidal fats and estuaries were developed, with abundant nutrients and sun light that support the proliferation of the biological activity of diverse type (bentonic and planktonic). The evolution of the Puncoviscana basin represents a change from a carbonate domain (Volcán Formation to the east) towards a clastic domain (Puncoviscana Formation) from the beginning of Cambrian.

Keywords : Puncoviscana Formation; Palaeoenvironment; Tidal; fat; Estuary; Fortunian.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )