Abstract

COLOMBI, Carina E et al. La Formación Balde de Leyes, una nueva unidad estratigráfica de la cuenca Triásica de Marayes-El Carrizal, San Juan. Rev. Asoc. Geol. Argent. [online]. 2015, vol.72, n.4, pp.445-455. ISSN 0004-4822.

The Marayes-El Carrizal Basin, Southeast San Juan province, Argentina, is composed of a continental succession deposit in a rift basin. The classical stratigraphy of the basin is defined in ascending order as follows: Esquina Colorada, Carrizal and Quebrada del Barro Formations. Remote sensing on satellite images, as well as sedimentological and paleontological studies, have allowed for identification of a new stratigraphic unit in the top of Quebrada del Barro Formation, crowning the Triassic succession in some areas of the basin. This new stratigraphic unit had previously been considered in geological maps and stratigraphic-paleontological studies to be part of the overlying El Gigante Group or the underlying Quebrada del Barro Formation. However, the finding of vertebrate fossils with remarkable Jurassic filiation in this unit led to dismissing this unit from the El Gigante Group. At the same time, significant differences in sedimentology-together with the characteristic Triassic filiation of the Quebrada del Barro Formation fauna-have now allowed for identification of this sedimentary succession as a new stratigraphic unit of the Marayes-El Carrizal Basin. The new stratigraphic unit is nominated Balde de Leyes Formation, whose name was assigned in accordance to its proximity to the homonymous locality, and leads to a new stratigraphic arrangement of the basin.

Keywords : Triassic; Jurassic; Marayes-El Carrizal Basin; Balde de Leyes Formation; Stratigraphy.

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