Middle to late Holocene environmental conditions inferred from paleosols at the perched dune in the Laguna Arturo, Fuegian steppe, southern Argentina

MUSOTTO, LORENA LAURA; BORROMEI, ANA MARÍA; CANDEL, MARÍA SOLEDAD; MEHL, ADRIANA; BIANCHINOTTI, MARÍA VIRGINIA; CORONATO, ANDREA

PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2022 vol. 588

0031-0182

In the present study, we carried out palynological (pollen, spores, fungal remains, andfreshwater algae) and pedological analyses from three paleosols (Ps6, Ps7, and Ps8) thatdeveloped in the upper part of the Arturo perched dune deposits, in the periphery of thehomonymous lake, and compared the results with modern palynological assemblagesfrom the Fuegian steppe in southern Argentina. These proxies offer an exceptionalopportunity to enhance our knowledge of environmental conditions during the Holocenein the southern high latitudes. Pollen spectra from the paleosols Ps6 (middle Holocene),Ps7 and Ps8 (late Holocene) were dominated by Asteraceae subf. Asteroideaeundifferentiated, which suggests that herbaceous and/or shrub vegetation probablydeveloped locally on the dune. The existence of herbivorous grazers is indicated by therecord of ascospores of several coprophilous fungi (Coniochaeta cf. lignaria, cf.Delitschia pachylospora, cf. Schizothecium sp., Sordaria-type, Sporormiella-type).Most other fungal remains (Glomus, cf. Cryptendoxyla hypophloia, Microthyriaceae,Alternaria sp., Dictyosporium sp.) are likely associated with the presence of steppevegetation communities. In general, the paleosols displayed a low degree of pedologicaldevelopment and in one of them (Ps7) there is evidence of the re-activation of eolianprocesses. Taken together, our palynological and pedological results, as well assedimentological and geomorphological data, indicate that Ps6 developed under lesshumid conditions than the overlying paleosols, Ps7 and Ps8. The variations in moistureavailability during soil forming intervals could be related to shifts in the latitudinalposition and/or strength of westerlies throughout the middle to late Holocene.