Merging Biostratigraphy, Cyclostratigraphy, Chemostratigraphy and U-Pb Dating for an Integrated Time Scale for the Hangenberg Crisis (belgium)

The Upper Devonian to lower Carboniferous strata of Belgium are of exceptional stratigraphic significance and have lent their names to internationally recognized stages (Frasnian, Famennian, Tournaisian, and Visean). The Devonian–Carboniferous boundary (DCB) is well exposed across Belgium, in depositional settings spanning shallow platform to deeper facies. Most of those records display clear sedimentary bundling patterns, interpreted as the imprint of orbital (Milankovitch) forcing. Among these, the Anseremme section stands out as a key reference locality and is considered as a potential candidate Global Boundary Stratotype Section and Point (GSSP) to replace the current GSSP. However, this section did not record any black shale layers associated with the Hangenberg crisis, while those are exposed through the Chanxhe record. By combining those two records, we can get a good overview of the succession of events through the DCB crisis. We integrate biostratigraphy, cyclostratigraphy and carbon-isotopes into a framework which is turned into a floating age model, including uncertainties. Within this framework, the carbon isotope signal appears strongly paced by orbital forcing, primarily precession and eccentricity. This cyclostratigraphic framework is then integrated with existing U-Pb geochronology using WaverideR. In addition, we also implement the Chanxhe record into astroBayes, which allows to build an age models through Bayesian statistical approach, combining both astrochronology and radioisotopic geochronology in a single statistical framework, resolving ambiguities between the two chronometers. The resulting age model provides a duration of 0.97 Myr to the Uppermost Famennian (or Strunian). The Hangenberg dark shales are interpreted to span ~65 kyr and the interval from the base of the dark shales to the Devonian-Carboniferous boundary is estimated to have lasted 280.2 kyr. The DCB itself is dated at 358.68 ± 0.305 Ma.