Reconstrucción de paleocomunidades arbóreas mediante análisis fitolíticos en sedimentos del Paleoceno superior-Eoceno? (Formación Las Flores), Chubut, Argentina.

BREA, M., ZUCOL, A. F., M.S. RAIGEMBORN Y S. MATHEOS.

Matices Interdisciplinarios en Estudios Fitolíticos y de otros Microfósiles/ Interdisciplinary Nuances in Phytolith and other Microfossil Studies

BAR Internacional Series (Oxford, Inglaterra).

Año: 2008; p. 91 - 108

In the Golfo San Jorge basin (Chubut, central Patagonia, Argentina), during the Upper Paleocene-Eocene?, an important fluvial cycle is developed whose sediments have been called the Rio Chico Group. This Group is conformed by three formations: Peñas Coloradas, Las Flores and Koluél Kaike. The studied sedimentary samples come from the Gran Barranca profile, in the Gran Barranca locality from the Lake Colhué Huapi (45° 43’ 26’’ S and 68° 37’ 14’’ W), Sarmiento, Chubut province. Two phytolith zones were recovered from Upper Paleocene-Eocene? sediments, with phytolith assemblages characterized by the abundance of dicotyledons phytoliths and palm phytoliths, associated with Poaceae, Cyperaceae and Podostemaceae phytoliths. Siliceous sponge spicules, Chrysostomataceae stomatocycts and diatoms have been found also in these assemblages. Nine Families and one Order were recognized: Arecaceae, Chrysobalanaceae, Mimosaceae, Magnoliaceae, Annonaceae, Burseraceae, Zingiberales, Poaceae, Cyperaceae y Podostemaceae. The palaeovegetations would have conformed humid tropical and subtropical forests, one dominate by woody dicotyledoneous and the other by palms. These forests were developed under warm and humid climatic conditions. The paleoxylologic records as well as the climatic inferences obtained through the sedimentological characteristics of these deposits support the existence of these climatic conditions for the Upper Paleocene-Eocene? in this region.