Interpretación paleoambiental del Grupo Mandiyutí (Carbonífero Superior): Evidencias palinológicas, sedimentológicas y tafonómicas

DI PASQUO, M.M.; AZCUY, CARLOS

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 1999 vol. 36 p. 71 - 81

0002-7014

Abstract. PALEOENVIRONMENTAL INTERPRETATION OF THE MANDIYUTI GROUP(UPPER CARBONIFEROUS),SALTA PROVINCE,ARGENTINA PALYNOLOGIC,SEDIMENTOLOGIC AND TAPHONOMIC EVIDENCES. In THE Argentine regionof Tarija Basin, the Mandiyutí Group includes two units: Escarpment and San Telmo Formations. Thestratigraphic section, around 700 meters thick, is located at the surroundings of Caraparí River, Salta province.The paleornicrofloral study was made with samples from a section of 100 m thick at the boundarybetween these units. The recognition of more than one hundred of miospore species with their botanicalaffinities has allowed to reconstruct five paleofloral communities, each one with particular hydrophyticrequirements. They have been defined as Paleocommunity A (lycophytes-sphenophytes), PaleocommunityB (filicophytes), Paleocomrnunity C (mainly monosaccate pollen grains), Paleocommunity D (poliplicatepollen grains), Paleocommunity E tBotrqococcus and other probable algae). Based on palynological. taphonornicand sedimentologic analyses from the studied section continental conditions are inferred. Atrencl of evolution for the depocentre, starting with a lacustrine system under humid conditions that endswith a drier alluvial plain, has been established. This paleoclimatic change is suggested by the appearanceof the Paleocornmunity D with Equisetosporites in the sample M445 of the middle section. It is also observeda change in the sediment color from grey in the lower and middle sections to red in the upper palynologicallybarren section. Finally, the observed transitional paleoclimatic evolution in this area of the TarijaBasin for the Carboniferous / Permian boundary is correlated with the same transitional change in otherArgentine basins from this periodo