New marine assemblage from the Jurassic-cretaceous boundary beds of the High Andes, Argentina

FERNÁNDEZ, M.; VENNARI, V.; HERRERA, Y.; CAMPOS, L.; TALEVI, M.; DE LA FUENTE, M. S.

Congreso; 10th Internatinal Congress on the Jurassic System; 2018

Jurassic marine reptiles from the southern margin of the Eastern Pacific have been documented since the XIX century. Most of them have been recorded at the Neuquén Basin (west-central Argentina) in sedimentites of the Vaca Muerta Formation (lower Tithonian-lower Valanginian). Outcrops of this lithographic unit in the southern sector of the basin have proven to be highly fosiliferous in marine reptiles (e.g. Cerro Lotena, Los Catutos and Pampa Tril, in the Neuquén Province; Gasparini and Dellapé, 1976; Pol and Gasparini, 2009; Gasparini and Fernández, 2011; Herrera et al., 2013). By contrast, exposures of the Vaca Muerta Formation in the northern sector of the Neuquén basin (Mendoza Province), though widely distributed, had not been prospected for marine reptiles since the middle of the XX century (e.g. Rusconi, 1938, 1948 a,b, 1967).During the last two years, a new field survey for marine reptiles was carried out in the southern Mendoza sector of the Neuquén Basin. Two cross-sections, 14 km apart, of the Vaca Muerta Formation were performed over the eastern flank of a NW-SE syncline: Arroyo Durazno (c. 260 m), located over the left margin of the El Durazno Creek, to the south, and Arroyo Paulino (c. 220 m), outcropping on the right margin of the Paulino Creek, to the north. At both localities the Vaca Muerta Formation consists of an intercalation of organic-rich laminated marls and nodular to massive limestones.During the last two years, a new field survey for marine reptiles was carried out in the southern Mendoza sector of the Neuquén Basin. Two cross-sections, 14 km apart, of the Vaca Muerta Formation were performed over the eastern flank of a NW-SE syncline: Arroyo Durazno (c. 260 m), located over the left margin of the El Durazno Creek, to the south, and Arroyo Paulino (c. 220 m), outcropping on the right margin of the Paulino Creek, to the north. At both localities the Vaca Muerta Formation consists of an intercalation of organic-rich laminated marls and nodular to massive limestones