ANCIENT COASTAL ENVIRONMENTS IN A MAASTRICHTIAN??PALEOCENE ATLANTIC SHORELINE: A PHYTOPLANKTON APPROACH

BOREL, CLAUDIA MARCELA; M.V. GULER; NAVARRO EDGARDO LUIS; ASTINI, RICARDO A.

PUBLICACION ESPECIAL - ASOCIACION PALEONTOLOGICA ARGENTINA

ASOCIACIÓN PALEONTOLÓGICA ARGENTINA

Año: 2016 vol. 16 p. 76 - 87

0328-347X

in this contribution we describe planktonic assemblages, comprising their taxonomic composition and palaeoecological attributes,from the La Colonia Formation, Patagonia, Argentina. The palynological samples are from the section exposed at Estancia San Miguel, in theTelsen area, Chubut province. Diverse organic-walled remains of Chlorophyta and Charophyta taxa are documented. These include coenobia oftwo species of Pseudopediastrum, colonies of Botryococcus and zygospores of the form-genus Ovoidites (resembling extant genera of Zygnemataceae).The green algae together with dinoflagellate cysts (analyzed in a previous detailed study) indicate brackish to freshwater and freshwaterdepositional conditions for the middle and upper part of the Estancia San Miguel section, respectively. These water bodies developedalong a coastal plain in the northern Patagonia probably during the Paleocene, in a phase of the extensive first transgressive event of the SouthAtlantic. The earliest record of Pseudopediastrum brevicorne for Patagonia is presented.