ABSTRACT: Acharophyte biozonation for the transitional and continental Upper Eocene-Lower Oligocene record in the eastern margin of the Ebro Basin is performed and calibrated using magnetostratigraphic data. This study has been based on intensive sampling collected along five composite sections. The Harrisichara vasiformis-tuberculata European biozone has been renamed to H. lineata biozone, since the former index-species was a poorly characterised morphotype with a non-valid species name. This biozone is represented in the transitional Sant Boi Formation and the lowermost part of the Artés Formation in the northeastern sector of the basin, within the normal part of chron C16. The Harrisichara tuberculata European superzone encompasses most of the continental Artés Formation in the northeastern sector and the Margalef Formation in the southeastern sector of the basin ranging from chron C16n.2n (~35.5 Ma) to chron C12r (~31.5 Ma). Included within the Harrisichara tuberculata superzone, the Lychnothamnus vectensis European biozone was redefined as the interval between the first occurrence of Lychnothamnus vectensis and the first occurrence of Lychnothamnus pinguis. Redefinition of the Lychnothamnus vectensis biozone implies that its basal limit does not coincide with the basal limit of the Harrisichara tuberculata superzone, as previously believed. The absence of L. pinguis in the Ebro Basin, and probably in all Southern Europe, results in a local Lychnothamnus vectensis biozone for that area including the total distribution range of this index species. Magnetostratigraphic correlation suggests that this biozone ranges in the Ebro Basin from chron C13r (~34.5 Ma) to chron C13n (~33.5 Ma) including the Eocene-Oligocene boundary. Anew local Harrisichara tuberculata-Nodosochara jorbae assemblage zone was defined at the base of Harrisichara tuberculata superzone coinciding with the base of the Artés Formation in the northeastern sector, ranging between chron C16n.2n and chron C13r. The Lychnothamnus major European biozone encompasses the lower part of the continental Albi Formation in the southeastern sector of the basin within chron C12r. The lower limit of the Chara microcera European biozone is recorded in the Tàrrega Formation. Litho- and magnetostratigraphic correlation suggests that the lower limit of this biozone belongs to the uppermost part of chron C12r (~31 Ma). Comparisons with homologous data from the classical Upper Eocene-Lower Oligocene Solent Group in the Hampshire Basin (Isle of Wight, UK) suggest that the lower limit of the Harrisichara tuberculata superzone is isochronous in Europe but was recorded earlier in the Ebro Basin than in the Hampshire Basin due to more appropriate palaeoecological conditions.
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