Syndesmorion stellatum (Fijałkowska) Foster & Afonin chloroficean algae and associated microphytoplankton from lacustrine successions of the La Veteada Formation (Late Permian), Paganzo Basin, Argentina. Paleoenvironmental interpretations and stratigraphi

GUTIERREZ, P. R.; ZAVATTIERI, A.M.; EZPELETA M.

REVIEW OF PALAEOBOTANY AND PALYNOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 p. 1 - 20

0034-6667

A diverse microphytoplankton assemblage recovered from terrestrial palynoflora-bearing deposits of the La Veteada Formation, north of the La Rioja Province, Paganzo Basin, Argentina, is described and illustrated. The ~180 m thick sedimentary type section of the unit in the Los Colorados anticline is composed of a basal grey silcrete covered by gypsum beds and a thick succession of purple mudstones inter-layered with varicolored fine sandstone sheets and laminated yellowish dolomites. The aquatic assemblage is mainly characterized by a great variety of Syndesmorion stellatum (Fijałkowska) Foster and et Afonin coenobia, recorded for the first time in Gondwanic realm. All the morphotypes described for this chlorophycean alga are recognized in this assemblage, and new polymorph-coenobia are described and illustrated. The genera Maculatasporites and Melhisphaeridium are commonly present, whose algal derivation is discussed. Two new combinations are proposed: Maculatasporites gondwanensis (Tiwari) new nov. comb., Maculatasporites amplus (Segroves) new nov. comb., Mehlisphaeridium parvum Anderson is emended, and Mehlisphaeridium regulare and Mehlisphaeridium sp. are also described and illustrated. Representatives of the zygnematacean algae, Brazilea scissa, B. plurigenus, B. sp. A, Tetraporina tetragona, ?Lecaniella sp., as well as large clusters of sphaeromorphs incertae sedis probably representing spores of that chlorophyta algae are described. In addition, planar colonial chlorococcalean Pediastrum-like forms suggesting hydrodictyaceaen algae are recorded for the first time in Late late Paleozoic strata of Argentina. Besides, Reduviasporonites chalastus as green algae of zygnematalean affinity is also considered. The diverse autochthonous chlorophycean algae assemblage colonized the hypersaline lacustrine environments as reveled by the lithology and sedimentology of the La Veteada Formation type section suggesting that they supported brackish-water conditions. In general terms, the land-derived palynological composition of the La Veteada assemblage at Central Famatina Range reflects parent vegetation adapted to arid or semi-arid climate as reported from late Guadalupian to late Lopingian in the Paganzo Basin. The whole palynological composition suggests a Lopingian age for the La Veteada Formation at its stratotype, based on the stratigraphic range of all the land-derived miospores species recognized, resulting younger than the eckisporites?Weylandites Biozone (LW: Wordiano?Capitaniano). Therefore, it is considered the youngest Permian palynofloral assemblage recorded up to now in Argentina and South America.