Sedimentología, paleontología y estratigrafía del límite Cretácico-Paleógeno en Liu Malal, Mendoza

PIRES, M.; NÁÑEZ, C.; CASADÍO, S.; PARRAS, A.

Salta

Congreso; 14º Congreso Geológico Argentino; 1999

Asociación Geológica Argentina

The stratigraphy, sedimentology and paleontology of the Malargüe Group at the Liu Malal locality (Mendoza Province) is analysed. The studied section, 121 m thick, is composed of two units. The lower unit (Jagüel Formation) is characterized by siliciclastic sediments, whereas the upper one (Roca Formation) is a thick succession of limestones and marls. Both units bear a diverse biota including bivalves, gasteropods, cephalopods, crustaceans, foraminifera, echinoderms and bryozoans. The seven sedimentary facies recognized suggest a subtidal to supratidal depositional paleoenvironment located mainly at an inner shelf. Six parasequences were recognized, three of them belonging to the Upper Maastrichtian and the remaining to the Danian. From detailed textural analysis of sediments and fossil assemblages, there are evidences supporting climatic change in the area during the Cretaceous-Paleogene boundary, which caused dryer and warmer conditions at the beginning of the Danian. The paleontological studies allow to place the Cretaceous-Paleogene boundary at the top of the Jagüel Formation