CONICET | Buscador de Institutos y Recursos Humanos

The Triassic Cuyo Basin is a prolific petroleum basin in Argentina with high rates of oil production. It corresponds to a passive continental rift system (Barredo, 2012), and extends over more than 60,000 km2, including the provinces of San Juan, Mendoza and San Luis (30º-34º LS). It is characterized by several depocenters that follow a NW-SE trend departing from the N-S trend of the present-day Andean chain. The Triassic stratigraphic record of the Cacheuta-Tupungato depocenter is represented, from base to top, by the Rio Mendoza, Cerro de Las Cabras, Potrerillos, Cacheuta and Río Blanco formations (Fig. 1). Most of the kerogen studies in the basin are based on light microscopy (e.g. Rojo & Zavattieri, 2006; Zavattieri & Rojo, 2006; Ottone, 2015; Pineda et al., 2020). The present contribution provides an integrated study of the organic matter in the studied section, and includes thermal maturity analysis and a paleoenvironmental evaluation of the Potrerillos-Cacheuta organic-rich shales. The study area is located in the Cerro Bayo (32º 57´8,1´´S 69º 12´48,4´´W), Potrerillos locality, west of Mendoza city (Fig. 1). A detailed sedimentological section of 1130 m thick was logged, from which seven outcrop samples were petrographycally analyzed (Fig. 2), five samples from the Cacheuta Fm (P26, P15, P17, P18, P19) and two samples from the upper Potrerillos Fm (P4A and P7B). Lacustrine deposits are recognized in the upper interval of Potrerillos Fm (Kokogián & Mansilla, 1989; Uliana et al., 1999) which exhibit similar sedimentological characteristic as the overlaying Cacheuta Fm. The latter is composed of black laminated shales interbedded with tuffs, fine-grained sandstones and grey claystones (Spalletti et al., 2005; Salduondo et al., 2020).

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