Programs and projects
Program 2030

Biological validation of carbonate-based proxies and application to the Middle Miocene onset of icehouse conditions and the closure of the Tethys: seasonality as a key factor
Program coordinator(s): Prof. dr. G. J. van der Zwaan
Theme(s): 2
Funding date: 13-apr-05

Understanding of the complex System Earth is urgently needed to predict effects of climate change in a world that is increasingly characterized by greenhouse conditions. Especially effects of abrupt changes on the biosphere from greenhouse to icehouse (and vice versa) conditions need to be better understood. In this context it is insufficiently realized that for the biosphere some elements of climate change are of considerably more importance than others. Climate change often is expressed more pronounced in one season, and often in one parameter (temperature, humidity). The resulting change in seasonality is a key factor in biotic evolution since marine and terrestrial organisms are dependent for reproduction on critical values of particularly temperature. We propose to reconstruct in detail temperature, salinity, and oxygenation of surface and bottom waters employing new proxies. We further aim at calibrating known proxies as isotopes and Mg/Ca ratios to reconstruct seasonality of temperature in detail. To establish the new proxies we aim to experimentally validate the relationship between Mg/Ca ratios and temperature in benthic foraminiferal shells. We also want to establish the efficiency with which redox metals are incorporated in the shells of living benthic foraminifera. In the second part of the program we will apply temperature proxies based on modern and fossil Mediterranean planktonic foraminifera in order to be constrain how seasonality developed over time. In the third part of the program we focus on the closure of the Tethyan Seaway between 15 and 10.5 Myrs because this is a prime example of a gradual process with abrupt, non-linear consequences. The Middle Miocene changes in the Mediterranean contributed to global climate changes including increased. The development of seasonal contrasts must have been instrumental to the evolutionary patterns of the terrestrial and marine domain at that time. We will reconstruct quantitative records (based on validated oxygen isotope, Mg/Ca records) of salinity and temperature for summer and winter planktonic foraminiferal taxa. We will further reconstruct oxygenation of bottom waters using the newly developed proxies based on redox metals incorporated in the benthic foraminiferal shell.

This program contains the following projects:
2031: Biological validation of proxies for temperature, salinity, oxygenation and pCO2 based on experimental evidence using benthic foraminiferal cultures
2032: Assessing the seasonality evolution in the Mediterranean Sea: calibration of carbonate-based proxies and application in selected time slices
2033: Application of carbonate-based proxies to the Middle Miocene onset of icehouse conditions and the closure of the Tethys: seasonality as a key factor

A.A. Mourik, J.F. Bijkerk, A. Cascella, S.K. Hüsing, F.J. Hilgen, L.J. Lourens, E. Turco (2010). Astronomical tuning of the La Vedova High Cliff section (Ancona, Italy)—Implications of the Middle Miocene Climate Transition for Mediterranean sapropel formation. Earth and Planetary Science Letters297: 249-261.
Darwin Center authors: Hilgen F. J., Lourens L. J., Mourik A.

Anja A. Mourik (2010). The Middle Miocene climate transition in the Central Mediterranean.
Darwin Center authors: Mourik A.

Wit JC, De Nooijer LJ, Barras C, Jorissen FJ, Reichart GJ (2012). A reappraisal of the vital effect in cultured benthic foraminifer Bulimina marginata on Mg/Ca values: assessing temperature uncertainty relationships. Biogeosciences9: 3693-3704.
Darwin Center authors: de Nooijer L.J., Reichart G. J., Wit J. C.

Jos Wit (2012). Calibration, validation and application of foraminiferal carbonate based proxies: Reconstructing temperature, salinity and seawater Mg/Ca.
Darwin Center authors: Wit J. C.