Age and palaeoenvironment of the "Serie del Yeso", Valle del Cura, San Juan Province: Palynological evidence.

A diverse and well preserved palynological assemblage is reported for the f irst time from the Upper section of the "Serie del Yeso", San Juan province , Argentina. The assemblage is dominated by herbaceous and shrubby forms of the families Cyperaceae, Poaceae, Malvaceae, Sympocaceae, Asteraceae, Anac ardiaceae and Ephedraceae which, on sedimentological and palynological grou nds, may have developed in the surroundings of a lacustrine environment. Tr ee components and ferns are very sparse. Fresh water algae, mainly Botryoco ccus, are abundant. A few dinoflagellate cysts and acritarchs are present i n this assemblage which may suggest brackish conditions in the lake. The gr eat development of gypsum seams in the Upper Section of the "Serie del Yeso " is in accord with this assumption. The spore-pollen assemblage suggests w arm to warm temperate and dry climate conditions. This assemblage also sugg ests a Miocene age for this unit, probably Middle Miocene. A new combinatio n, Mutisiapollis viteauensis (Barreda) Barreda comb. nov., is here proposed . Cyperaceaepollenites neogenicus Krutzsc 1970 and Tetracolporites spectabi lis Pocknall and Mildenhall 1984 are reported for the first time from Argen tina.