A high precision U–Pb radioisotopic age for the Agrio Formation, Neuquén Basin, Argentina: Implications for the chronology of the Hauterivian Stage

Abstract

A new CA-ID TIMS U–Pb age of 130.39 ± 0.16 Ma is presented here from the Pilmatué Member of the Agrio Formation, lower Hauterivian of the Neuquén Basin in west-central Argentina. This high precision radioisotopic new age, together with the two former ones from the upper Hauterivian Agua de la Mula Member of the Agrio Formation and modern cyclostratigraphic studies in the classical sections of the Mediterranean Province of the Tethys indicate that the Hauterivian Stage spans some 6 Ma, starting ca. 132 Ma and ending ca. 126 Ma. These radioisotopic ages are tied to ammonite biostratigraphy and calcareous nannofossil bioevents and biozones recognized in the Neuquén Basin which in turn are correlated with the Mediterranean standard zones. A new geological time scale for the Valanginian–Hauterivian stages in the Mediterranean region integrating astrochronological and radiochronological data differs with the current official geological time scale which still maintains poorly constraint absolute ages for the Berriasian-Aptian interval.