Pollen and spores from the Anadia Basin (West portuguese coastal margin) as stratigraphic and environmental indicator

The Anadia basin, situated along the contact betweenthe Variscan Iberian massif and western Portuguese coastal margin, is an elongated basin (up to 10 km wide and 50 km long). The chronostratigraphy of the infill deposits is not well established but a previous study, based on sedimentological data, point to the Pleistocene-Holocene. Two cores were selected for palynological study. The sediments altemate between sand and clays almost sterile from the paleontologic point of view, with some lignites relatively rich in palynomorphs. Also, an outcrop with a 2 meters thick lignite level have been sampled (20 samples). The pollen spectra from both cores and the outcrop shows the dominance of Pinaceae and Ericaceae followed by the spores (Pteridophyta and Bryophyta). The mesothermic trees, like Quercus, Alnus, Liquidambar, Acer, Carya and Salix are well represented, and the mega-mesothermic forms such as Taxodiaceae, Myrica, Engelhardia, Symplocus and Nyssa are present. Cathaya,Tsuga and microthermic plants (Abies and Picea) are present in small amounts. The herbs are dominated by, Asteraceae, Poaceae and Amaranthaceae-Chenopodiaceae. The high percentage of spores, Liquidambar, Alnus and other palynomorfs like Zygnemataceae seems to indicate a swamp habitat with long hydroperiods surrounded by mixed and diverse swamp florests composed of woody angiosperm and Pinaceae. The comparison between the palynological association from Anadia basin with those from Rio Maior, a reference basin for the portuguese Pliocene, suggest a middle Pliocene age (Piacenzian), due to the presence ofthermophilous elements such as Taxodiaceae, Cathaya,Symplocus and Nyssa.