Tidally dominated rimmed shelf facies of the Picún Leufú Formation (Jurassic/Cretaceous boundary) from southwestern Gondwanaland, Neuquén Basin, Argentina

ARMELLA, CLAUDIA; CABALERI, NORA; LEANZA, HÉCTOR

CRETACEOUS RESEARCH (PRINT)

Elservier

Lugar: London; Año: 2006 p. 1 - 34

0195-6671

A palaeoenvironmental model for the Picún Leufú Formation (Jurassic/Cretaceous boundary) cropping out in the Neuquén Basin (Argentina) at the southwestern margin of Gondwanaland, is presented in this paper for the first time. Detailed stratigraphic sections exposed at national road nº 40 where it crosses the Picún Leufú creek (type locality) and in the Cerrito Caracoles area, were examined and sampled. Based on the combination of the sedimentological data obtained (facies/microfacies analysis) and the relationship between benthic macrofaunas and their taphonomic attributes, it is concluded that the Picún Leufú Formation represents a tidally dominated rimmed shelf setting characterized by prograding bars dissected by channels and thick lagoonal facies with shoal developments. In the Cerrito Caracoles area, where only its basal part is exposed, the Picún Leufú Formation seems to have been deposited in a shallow subtidal marine environment, where shelf margin facies with patch reefs have been recognized. The paper was finnancially supported by CONICET (PEI 87/97)