Biostratigraphy of Cambrian-Ordovician conodonts from the Los Sombreros Formation, western Precordillera, Argentina

TORRE, GABRIELA; ALBANESI, GUILLERMO

Novosibirsk

Congreso; International Symposium on the Ordovician System; 2019

IGCP

The Los Sombreros Formation corresponds to the western tectofacies (Astini, 1991) of the Argentine Precordillera. This formation crops out in the Tontal Range (Cuerda et al., 1984) to the south of the San Juan river up to the latitude of Jáchal City (Benedetto and Vaccari, 1992) and the Ancaucha River (Albanesi et al., 1995). This exposure constitutes a significant piece for the interpretation of the Precordilleran continental slope. Without considering the structural complexity and the scarcity of the fossil record to determine a detailed depositional scheme, a spectrum of ages ranging from the Ordovician to the Devonian was proposed for the Los Sombreros Formation (Benedetto and Vaccari, 1992; Albanesi et al., 1995; Peralta, 2005). Recently, Voldman et al. (2018) documented the appearance of conodont species from the upper Furongian and upper Tremadocian found in gravity flow deposits with sinsedimentary deformational features, which suggest the existence of an active continental slope from the late Cambrian until the Middle Ordovician.New conodont records are reported in the present contribution for the Los Sombreros Formation in the Tontal and Yerba Loca ranges (Fig.1). The consequent biostratigraphic data are significant to determine the correspondence of this formation with the sedimentary source in the carbonate platform of the Precordillera, as well as for precise geological correlation to intercontinental scale.