El cambio de los foraminíferos bentónicos en el pasaje Cretácico-Paleógeno, cuencas Neuquina y del Colorado, Argentina

MALUMIÁN, NORBERTO; CARAMÉS, ANDREA; NÁÑEZ, CAROLINA

Trelew

Congreso; VI Congreso Argentino de Paleontología y Bioestratigrafía; 1994

A late Cretaceous transgression and a subsequent Paleocene regression is recorded in the foreland history of the Neuquén Basin of western Argentina. At this time there was a closed off to the north and west creating an embayment dominated by tidal currents, with deposition of mixed carbonate-siliciclastic sediments and evaporites. The Cretaceous-Paleogene boundary is contained in the Jagüel Fm. (Neuquén Basin) and in the Pedro Luro Fm. (Colorado Basin).      A major faunal turnover occurred in shallow benthic foraminiferal faunas across the Cretaceous-Paleogene boundary in the Neuquén-Colorado Basins. 92 species are recorded in the Middle-Upper Maestrichtian, with 17,4% of them surviving into the Tertiary; eight species are endemic restricted to these basins, seven of them becoming extinct before or at the K/P boundary. The Danian sediments bear a cosmopolitan midwayan assemblage, with only one frequent endemic species which is restricted to southern South America and Antarctica; the 13,4% of the 119 Danian benthic species are also recorded from the Maestrichtian.      A preliminary analysis of the paleoecologic response indicates that from inferred life position, the Maestrichtian infaunal benthic foraminiferal species seem to be more abundant than the Danian ones. Palabras claves: Foraminíferos bentónicos, límite Cretácico/Paleógeno. Patagonia. Cuenca Neuquina. Cuenca del Colorado. Key words: Benthic foraminifera, Cretaceous/Paleogene Boundary. Patagonia. Neuquén Basin. Colorado Basin.