Astronomical calibration of the Danian Stage (Early Paleocene) revisited: settling chronologies across the Atlantic and Pacific Oceans

Abstract

The astronomical time scale for the Paleocene is hampered by some uncertainties including discrepant number of 405-kyr eccentricity related cycles and correlation schemes among key records being proposed by different authors (Westerhold et al., 2008; Kuiper et al., 2008; Hilgen et al., 2010). Here we present a new Danian correlation framework resolved at the ~100-kyr short-eccentricity level between the land-based Zumaia and Sopelana hemipelagic sections from the Basque Basin and deep-sea records drilled during ODP Legs 198 (Shatsky Rise, North Pacific) and 208 (Walvis Ridge, South Atlantic) that reconciles both the magnetostratigraphy and the short and longeccentricity cycle patterns among the records and, hence, improves synchroneity of events. The correlation has been aided by composite images from ODP cores and a new wholerock 13C isotope record at Zumaia while its original magnetostratigraphy (Dinarès-Turell et al., 2003; 2010) is reinforced by new data from Sopelana. Notably, we challenge the correlation of the Pacific Sites 1209–1210 that were offset by as much as one 405-kyr cycle in previous interpretations (i.e., the Fasciculithus spp. LO, which approximates the Danian–Selandian (D–S) boundary, and the “Top chron C27n” climatic event were at odds between oceans in the interpretation of Hilgen et al. (2010). It is found that the Danian consists of 11 (and not 10) consecutive 405-kyr eccentricity cycles. The new consistent stratigraphic framework enables accurate estimates to be made of ages for magnetostratigraphic boundaries, bioevents, and sedimentation rates. Low sedimentation rates appear common in all records in the mid- Danian interval along the upper part of chron C28n, including conspicuous condensed intervals in some of the oceanic records that in the past have hampered the proper identification of cycles. The new chronological framework, spanning a duration of about 4.5 My, allows assessing the role of orbital forcing on the paleoclimatic variability as registered by the related isotope records. It appears clear that there exists a periodic beat at the 100-ky and 405-ky eccentricity cycles impressed in the record. The phase relationship between the benthic isotope record and eccentricity is similar to patterns documented for the Oligocene and Miocene, as indicated by others, confirming the role of orbital forcing as the pace maker for paleoclimatic variability on Milankovitch time scales. The preferred tuning to the La2011 orbital solution provides astronomically calibrated ages of 66.022±0.040 Ma and 61.607±0.040 Ma for the (D–S) and Cretaceous–Paleogene (K–Pg) boundaries respectively. Finally, we envisage that the Zumaia section, which already hosts the Selandian GSSP, could serve as the global Danian stratotype.