Significant efforts have been undertaken to improve scientists’ understanding of the time scales and processes affecting the climate and ocean dynamics roughly 66–145 million years ago during the Cretaceous. Often described as Earth’s “greenhouse” time, the Cretaceous featured plate configurations, ocean circulation, carbon dioxide concentrations, sea surface temperatures, and salinity that differed considerably from modern-day conditions.
Widespread deposition of organic carbon-rich sediments during oceanic anoxic events (OAEs; times of total depletion of dissolved oceanic oxygen) reflects peculiar oceanography and biogeochemistry. These OAEs were marked by large equatorial upwelling zones in the Pacific, Atlantic, and Tethys oceans, coupled with widespread anoxia in the Atlantic and western Tethys oceans.
Paleoceanographic and paleoclimatic topics of the Cretaceous were the focus of a workshop last October in Sicily, Italy. Participants included 28 scientists of different nationalities with expertise in astronomy, paleontology, sedimentary geology, stratigraphy, geochronology, geochemistry, and climate and ocean modeling.
Seven keynote lectures given by experts in the different fields provided insight into the state-of-the-art research into the entire Cretaceous Earth system, with particular focus on
- climate dynamics and evolution of marine and terrestrial biota at times of changing climate
- exploration of new tools providing more reliable calibration of the Cretaceous sedimentary records, including astrochronology
- analysis of climate and ocean dynamics during the Cretaceous OAEs
Speakers summarized developments in recording Cretaceous stratigraphy and assessed and discussed gaps in the knowledge of the fine details of the geological time scale within the Cretaceous, which are particularly due to the limited availability of radiometric dated records, precise integrated stratigraphy, and reliable and accurate orbital tuning of sedimentary sequences.
Working group sessions formed the core of the workshop. One working group provided a road map for future investigation in stratigraphy and the development of accurate and reliable age models based on astrochronology combined with other stratigraphic methods. Another working group focused on aspects of physical, chemical, and biological oceanography at times when Earth’s orbital configuration changed during Cretaceous greenhouse and icehouse intervals.
A third working group identified future research themes in the field of paleoceanography at times of OAEs, which are seen as the global oceanic expression of major carbon cycle perturbations. This group also discussed questions concerning possible links between the carbon cycle and changes in carbon dioxide concentrations, as well as related temperature trends. A fourth working group discussed future needs regarding the modeling of physical and biogeochemical parameters using improved empiric data.
For more details on specific sessions and working groups, visit the workshop’s website.
The workshop was supported by the European Science Foundation’s Research Networking Program, under the umbrella of the European Union’s Earthtime program. We thank E. Erba, S. Flögel, and H. Weissert for their crucial contributions to this report and all the workshop participants for their constructive and enthusiastic input.
—Mario Sprovieri, Institute for Coastal Marine Environment, National Research Council, Capo Granitola, Italy; email: [email protected]
Citation: Sprovieri, M. (2015), Climate and ocean dynamics during the Cretaceous, Eos, 96, doi:10.1029/2015EO027139. Published on 27 March 2015.