Palynological study of a sedimentary profile from the middle-late Holocene, western Iberá, Corrientes, Argentina

Abstract

With the denomination "Iberá", we identify one of the most important tropical wetlands of the biosphere in terms of its extension and living species, both animal and vegetal. The objective of this paper is to reconstruct the predominant plant communities and their variations, infer the changes in the climatic conditions that would have occurred and to deduce the depositional environment during the middle and late Holocene in the Iberá region. The profile was sampled in a ravine located in the central zone of the western margin of the Iberá System, in the locality of San Miguel. The dynamics of the vegetation and the relation of the taxa allowed establishing three pollen zones: Pollen Zone I (middle Holocene) presents a characteristic association of steppe grass. The identified lithofacies suggests a depositional environment of waterlogged valleys, which together with the recognized vegetal palaeocommunities, would indicate humid conditions for the middle Holocene. Pollen Zones II and III (late Holocene) show an association characteristic of the herbaceous psammophyte steppe. The observed Brassicaceae increase would indicate environmental disturbances, which could reflect the combination of intense wind action under an arid climate. The identified lithofacies give evidence for an eolian environment with fluvial spills and indicate together with the recognized vegetal communities, arid to semi-arid conditions for the late Holocene.