![]() The validated magnetobiochronological plot was used to obtain pixel data corresponding to the limits of the biozones of interest. Calcareous nannoplankton biozones: I, II, ,, and III planktonic foraminiferal biozones: IV, V, VI, VII. (see references therein ) are plotted against timescale using age model from Gradstein et al. ![]() Benthic foraminifera δ 13C and δ 18O data from Zachos et al. Validated Paleogene magnetobiochronological scale. ![]() After this adjustment, the re-scaling of the Paleogene magnetobiochronological scale was validated ( Fig. 1). This implies that the length of the Eocene had to be reduced by a factor of 0.9698, whereas the Paleocene had to be expanded by a factor of 1.1075. For this re-scaling, we considered that the Cretaceous-Paleogene boundary and the Paleocene-Eocene boundary are anchored at 66.0225 and 55.93 Ma respectively, following the specifications in. In spite of this, curves still did not fit properly at the Paleocene-Eocene boundary, thus a second re-scaling was applied. by a stable isotope record based on an updated age model, which extends from the late Maastrichtian up to the early Eocene. To solve this, we replaced δ 13C and δ 18O data from Zachos et al. However, the negative excursion of δ 13C values did not coincide with the Paleocene-Eocene boundary. We observed a perfect fit between isotope curves and chronostratigraphic and biostratigraphic schemes. At the Paleocene-Eocene boundary, a large amount of isotopically light carbon was added into the ocean-atmosphere system causing a unique negative excursion of δ 13C values at the Eocene-Oligocene boundary, a notable increase in δ 18O values is recorded reflecting the beginning of Oligocene glaciation. Well-known global stable isotope shifts that characterize the boundaries of some epochs allowed us to validate the Paleogene scale. ![]() In order to validate the obtained Paleogene magnetobiochronological scale, carbon and oxygen isotope data from Zachos et al. Following the results in Table 3, the re-scaling process of numerical age, chronostratigraphical and biostratigraphical scales was done in Adobe Illustrator, and a single plot for the entire Paleogene was obtained. Here, we followed the age model of Gradstein et al. The age of these chrons was obtained from the ODSN website, which provides numerical ages according to different timescale models for magnetic events. In order to standardize the vertical scale, we looked for the numerical age of key chrons, i.e., the first and last complete chrons of each epoch, as well as the chrons within the boundary intervals between epochs (Paleocene-Eocene and Eocene-Oligocene Table 1). Since the epoch plots were separated in Berggren and Pearson, different vertical scales were used in each plot. Such additions consisted of the digitization of the new biozones together with a reference biozonation that allowed us to place them correctly into the plot. Other calcareous nannoplankton and planktonic foraminifera biozones were added to the constructed plot. We thus joined them in a single plot by overlapping the contiguous biozones. In Berggren and Pearson, these scales are shown by epoch, and only some chrons and biozones of the contiguous epochs are indicated in each case. We digitized the Paleocene, Eocene and Oligocene chronostratigraphical and biostratigraphical (including calcareous nannoplankton and planktonic foraminifera biozones ) time scales as integrated by Berggren and Pearson.
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