Bioestratigrafía basada en quistes de dinoflagelados del Neógeno en el noreste de la Patagonia, Argentina

GULER, M.V; SCASSO, R.A; FUENTES, S.N.; PALAZZESI, L.; CUITIÑO, J.I.; BARREDA, V.D

REVISTA BRASILEIRA DE PALEONTOLOGIA

SOC BRASILEIRA PALEONTOLOGIA

Lugar: Porto Alegre; Año: 2016 vol. 19 p. 303 - 314

1519-7530

BIOSTRATIGRAPHY BASED NEOGENE DINOFLAGELLATE CYSTS IN NORTHEAST OF PATAGONIA, ARGENTINA. This paper presents the biostratigraphic results based on dinoflagellate cysts from two Neogene lithostratigraphic units 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 Península Valdés, Chubut Province. The low-to-moderate diverse dinoflagellate cyst assemblages present are dominated by neritic taxa 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. The stratigraphic range of Labyrinthodinium truncatum truncatum in the lower part of the Barranca Final Formation indicate age between the late Burdigalian (ca. 16.5 Ma) and the late Tortonian (ca. 7.5 Ma) time interval. Labyrinthodinium truncatumtruncatum and Habibacysta tectata constrain the age of the Puerto Madryn Formation to the Serravalian to Tortonian interval (late middle miocene to early late Miocene). Theses ages are consistent with the 87Sr/86Sr isotopic analysis of the oyster valves at 9.61 and 8.3 and with the 87Sr/86Sr ratios on calcitic shells at about 10 Ma, respectively.