Towards an orbitally-tuned Maastrichtian stage

• Applicant: Professorin Dr. Silke Voigt
• Subject Area: Geology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 530461673

The latest Cretaceous witnessed perturbations in the global carbon cycle assumed to have been associated to climatic cooling and potential ephemeral glaciations. In order to understand the forcing mechanisms, their global significance, and the regional response to these events it is necessary to improve our presently available stratigraphic framework. Recent advances in Maastrichtian astrochronology allowed for the tuning of carbon cycle variations to the metronome of the 405-kyr long eccentricity cycle. However, all studied time series do not cover the Campanian-Maastrichtian transition between 73 and 71 Ma, a critical interval of severe climatic cooling. The cyclic limestone succession at Tercis-les-Bains in SW France records carbon isotope perturbations and is the ratified GSSP for the base of the Maastrichtian. However, actually the resolution of carbon isotope stratigraphy is too low to assess potential orbital forcing mechanisms of the Earth’s exogenic carbon cycle. Further, the definition of biostratigraphic events as first and last occurrences of calcareous nannofossils and planktonic foraminifera is not precisely resolved yet. Here, we propose to develop an astrochronology together with a high-resolution carbon isotope stratigraphy at the GSSP section of Tercis-les-Bains using bulk-carbonates to resolve short-lived isotopic events on orbital timescales between 73 and 71 Ma. The development of such an integrated stratigraphic framework is important for global correlation between shelf and oceanic sections as well as between low and high-latitudes. It will further allow reassessing the GSSP by providing a precise boundary definition relative to the geomagnetic polarity time scale. Results of this project will provide a robust stratigraphic framework on orbital time scales necessary to recognize temporal relationships between the carbon cycle, changes in ocean chemistry, circulation and sea level, and the oceanic ecosystem response.

• DFG Programme: Research Grants
• International Connection: Denmark, France, Poland, Spain
• Cooperation Partners: Sietske Josephien Batenburg, Ph.D.; Dr. Agata Jurkowska; Professor Mathieu Martinez, Ph.D.; Dr. Nicolas Thibault