Micropaleontología en materiales holocenos de la Ría de Gernika (Golfo de Vizcaya)

• Autores: Ana Pascual Cuevas, Julio M. Rodríguez Lázaro
• Localización: Geogaceta, ISSN 0213-683X, Nº. 20, 1, 1996, págs. 209-213
• Idioma: español
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  • Microfossils (foraminifera, ostracoda) from six cores of the Holocene of the Ria of Gernika (Southern Bay of Biscay) have been analysed in order to establish the paleoecological evolution of this area. Two kinds of paleoecologic assemblages of these organisms: 1) inner-shelf marine (coastal) and 2) estuarine (eurihalyne) and their repartition along the seriesshow the presence of active channels (intervals with marine and/or estuarine microfaunas) and the subsequent filling of the channels (intervals with very rare or absent microfaunes). Three main depositlonal phases can be differentiated: a first one with estuarine subenvironments (sandy-muddy intertidalchannel, vegetated marsh, schorre) of about 3500 yr BP; a second phase with the entrance of allochthonous specimens from the intertidal and inner platform, carried by tidal currents that increase the assemblage diversities of the microfaunas. This entrance of marine waters may correspond with a transgression of the Subatlantic stade (c. 3000-2500 yr BP) previously described. A third phase, with scarce microfauna, filling of several channels and increase of the schorre areas, is partly a consequence of the antropic action during the last 3 centuries, when changes in the location of the channels altered the whole estuary