SECUENCIAS DEPOSITACIONALES DEL GRUPO MALARGÜE y EL LÍMITE CRETÁCICO-PALEÓGENO, EN EL SUR DE LA PROVINCIA DE MENDOZA, ARGENTINA

Abstract

The sequence stratigraphic analysis of the Malargüe Group in the south of Mendoza Province, allows the recognition of five depositional sequences. The first sequence is attributed to a river-dominated delta and lake setting and the second to a river-dominated delta transitional to a tide-dominated delta (continental to marginal marine facies); both are assigned to the Loncoche Formation. The third sequence was deposited in a subtidal to intertidal environment; it contains Maastrichtian fossils and is referred to the Roca Formation. The fourth sequence is attributed to lacustrine and fluvial environments, and the fifth is indicative of fluvial conditions; both are assigned to the Pircala Formation. The paleontological evidence and two 40K-40Ar radiometric ages indicate that, in this area of the basin, the Cretaceous-Paleogene boundary lies in the continental deposits of Pircala Formation (depositional sequence IV). From this, we conclude that at the beginning of the Danian, the northern boundary of the "Rocanense Sea" lie south of 36° S.

KEY WORDS. Sequence stratigraphy. Cretaceous-Paleogene boundary. Malargüe Group. Mendoza Province. Argentina.