Flora angiospérmica de Pico Quemado, Formación Ñirihuau (Oligoceno tardío), provincia de Río Negro, Argentina

CAVIGLIA, N, ; ZAMALOA, M.C.

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2014 vol. 51 p. 209 - 225

0002-7014

Abstract. ANGIOSPERM FLORA OF PICO QUEMADO, ÑIRIHUAU FORMATION (LATE OLIGOCENE), RÍO NEGRO PROVINCE, ARGENTINA. Pico Quemado is located East of San Carlos de Bariloche, and stratigraphically placed in the lower member of the Ñirihuau Formation (late Oligocene ? middle early Miocene). Fossil leaves (compressions and/ or impressions) of dicotyledonous angiosperms were studied and twenty two morphotypes are described. The families identified were Nothofagaceae, Myrtaceae, Rosaceae, Myricaceae, Malvaceae and Fabaceae and the genus Nothofagus Blume was found to be the dominant. The macroflora is compared with twenty two tertiary paleofloras from Patagonia, and similarity indices obtained by the Jaccard coefficient, yielded values less than 13 %. This low index could be explained as due to the younger age of the Pico Quemado paleoflora compared to most of the other paleofloras and/ or because it thrived at a lower paleolatitude. The paleofloristic analysis suggests a temperate to cold-temperate climate and no analogous vegetation among other known Patagonian fossil floras.