The Lanipustula Biozone in Patagonia: stratigraphic extensión, faunal changes, paleoclimatology and paleoecology

PAGANI MARÍA A; TABOADA ARTURO C; ISBELL, JOHN; FRAISER MARGARET L; DINEEN, ASHLEY; PAULS KATHRYN N

General Roca

Encuentro; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2012

Asociación Paleontológica Argentina e Instituto de Investigaciones en Paleobiología y Geología, Universidad Nacional de Río Negro

The Pampa de Tepuel and Mojón de Hierro formations in the Tepuel-Genoa Basin (Patagonia) constitute a succession that may contain as many as 6 glacimarine and glaciallly-influenced marine horizons separated by non-glacial intervals. Thus, these strata represent the thickest and most complete record of polar conditions for the Late Paleozoic Ice Age (LPIA). The Lanipustula Biozone is recognized in the Pampa de Tepuel Formation. The Pampa de Tepuel Formatios was deposted in a posible shelf edge and slope settin. Coarse clastics would have been introduced into the sites during deposition of fines from meltwater plumes and coarse particles as iceberg rafted debris. Diamictites were also deposited by debris flows. Grooved surfaces are the result of slide/glide planes and posible iceber keel marks. The Lanipustula Biozone is at least 450 m thick and four fossil-bearing levels are recognized, in all of them the Lanipustula patagoniensis Simanauskas (1996) is recognized, but the diversity, abundance and faunal comosition changes from the base to top. Upward, faunal changes represent changing environmental and paleoecological conditions. The lowstand may have allowed for more oxygenated and possibley brackish waters due to the proximity of shallower agitated waters and the introduction of freshwater from glaciers and deltas. The slump and slide blocks as well as ?turbidity currents? and posible bottom currents may have brought oxygen into the área where these features are present.