Bioestratigrafía de la Formación Puncoviscana (Neoproterozoico-Cámbrico inferior), en el Sector Oriental de Rio León, provincia de Jujuy.

ZAMPONI, MAURICIO; LÓPEZ DE AZAREVICH, V.; AZAREVICH, M.B; CHILIGUAY, WALTER J.; GUILLERMO F. ACEÑOLAZA,

Salta

Simposio; Controles modernos y antiguos en sistemas sedimentarios; 2017

CEGA-INSUGEO-CONICET

Bioestratigraphy of the Puncoviscana Formation (Neoproterozoic-Early Cambrian) in the Eastern Sector of the Río León, Jujuy province. The finding of medusoids and conulariformes in Puncoviscana Formation, 25 km north of San Salvador de Jujuy, motivated a biostratigraphic study in Quebrada de León. We work in the eastern half of these outcrops where three profiles are made. From the sedimentary structures in common was observed: massive sandstones, linguoid, straight to sinuous ripples, turboglyphs, undulitic stratification, channels, hummocky type stratification, tidal rhythms and runoff marks. This registry guides us to a coastal marine environment from beach to areas to shallow platforms. The record of Corymorpha sp in Profile 1A is important because it is a paleoenvironmental indicator because it has protective rings that allowed it to live in areas of waves. Another hydrozoan of similar habitat and similar basic characteristics is Tubularia crocea (Agassiz 1862) (Family Tubulariidae), found in Profile 2. These cnidarian fossils corroborate the paleoenvironmental interpretation performed by sedimentological interpretation, to which must be added actinic anemones and microbial forests. The study allowed the discovery of a new organism denominated to date "conulariformes" from young specimens of 3 centimeters long were collected to a mold of 6 centimeters in the oral region and 20 centimeters in length. The traces of the children are scarce; a sample of cruzianiformes stands out.Profile 1C recognizes a calcareous sandstone with beige limestone clasts. The origin of these fragments that reach 18 centimeters long would correspond to the Volcan Formation. Interpretation allows assigning to the Volcán Formation as older than Puncoviscana Formation.To approximate the age of these leptosedimentos the only guide is cruzianiforme icnosp that allows assigning to these sequences to Fortuniano.Conclusions-The sedimentological and fossiliferous study of the area lead to consider this portion of the basin as a shallow platform environment to the beach area.- More fossil specimens of a new organism called conulariformes- The presence of cruzianiformes gives this lepsedimentary sequence a Fortunian age.-Clasts of limestone in calcareous sandstones allow confirming that Volcán Formation is older than Puncoviscana Formation