Primer registro en superficie de sedimentitas continentales del Cretácico Superior en la cuenca del Colorado, sureste de La Pampa

CASADÍO, S.; MANERA, T.; PARRAS, A.; MONTALVO, C.; CORNACHIONE, G.

REVISTA DE LA ASOCIACIÓN GEOLÓGICA ARGENTINA

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 2000 vol. 55 p. 129 - 133

0004-4822

Outcrops of continental Cretaceous deposits on the western edge of the Colorado Basin, south-east of La Pampa Province, are described. The outcrops are small and restricted to two localities. However, from information obtained from them and from the subsurface, it is possible to establish that the Cretaceous deposits lie in a graben, which is bounded by north-west - south-east normal faults, and which wedge out to the north-east. The sedimentary rocks rest on crystalline basement, but the contact is not visible at the surface. Only the upper part of the section, which consist of 3 m of medium to conglomeratic sandstones and conglomerates in coarsening-up sequence is exposed suggests active tectonism in the graben. The facies association represents mid to distal alluvial fan environment. The sedimentary rocks studied here are assigned to the Colorado Formation and, because of the presence of eggshells and crushed eggs tentatively  recognized as sauropods, a Campanian-Maastrichtian age is suggested.