BIOESTRATIGRAFÍA BASADA EN QUISTES DE DINOFLAGELADOS DEL NEÓGENO EN EL NORESTE DE LA PATAGONIA, ARGENTINA

FUENTES SABRINA; M.V. GULER; J.I. CUITINO; L. PALAZZESI; R. SCASSO ; R. SCASSO; V.D. BARREDA

REVISTA BRASILEIRA DE PALEONTOLOGIA

SOC BRASILEIRA PALEONTOLOGIA

Lugar: Porto Alegre; Año: 2016

1519-7530

ABSTRACT ? BIOSTRATIGRAPHY BASED NEOGENE DINOFLAGELLATE CYSTS IN NORTHEAST OF PATAGONIA,ARGENTINA. This paper presents the biostratigraphic results based on dinoflagellate cysts from two Neogene lithostratigraphicunits cropping out in northeastern Patagonia. The Barranca Final Formation, located in the southwestern Colorado Basin, isexposed along the northern coast of San Matías Gulf, Río Negro Province, and the Puerto Madryn Formation in the PenínsulaValdés, Chubut Province. The low-to-moderate diverse dinoflagellate cyst assemblages present are dominated by neritictaxa with subordinate oceanic indicators. Towards the top of both sections, the relative frequencies of the dinoflagellate cytsdecrease, whereas acritarchs and continental palynomorphs proportions increase, indicating a shallowing upwards trend. Thestratigraphic range of Labrynthodinium truncatum truncatum in the lower part of the Barranca Final Formation indicate agebetween the late Burdigalian (ca. 16.5 Ma) and the late Tortonian (ca. 7.5 Ma). Labrynthodinium truncatum truncatum andHabibacysta tectata constrain the age of the Puerto Madryn Formation to the Serravalian to Tortonian interval (late middlemiocene to early late Miocene). Theses ages are consistent with the 87Sr/86Sr isotopic analysis of the oyster valves at 9.61and 8.3 and with the 87Sr/86Sr ratios on calcitic shells at about 10 Ma, respectively.