Program > By author > Ait-Itto Fatima-Zahra

We propose to establish a new astronomical time scale for the Aptian-Albian transition from the Col de Pré Guittard section (GSSP Albian, Vocontian Basin, SE France) and investigate the correlation between the long Milankovitch cycles and the occurrence of four laminated black shales events: Jacob, Kilian, Paquier, and Leenhardt, collectively known as OAE 1b. The spectral analyses performed on magnetic susceptibility signals reveal the strong influence of precession, 100-kyr and 405-kyr eccentricity cycles. Using the number of 405-kyr eccentricity cycles, the duration of the interval containing the Jacob to Leenhardt levels is calculated at 4.03 million years (Myr), while the durations of the Jacob, Kilian, Paquier, and Leenhardt events are respectively calculated at 1.55 Myr, 1.62 Myr, and 0.93 Myr. The occurrence of these events is not directly related to the Milankovitch cycles, but they are recorded near the local maxima of the 405-kyr filter. Our findings demonstrate that the 405-kyr eccentricity has influenced the recurrence of anoxic levels in the Vocontian Basin, although other factors, such as the placement of traps or oceanic basalt plateaus, have also contributed to the development of larger-scale marine anoxia.