Project A6

Seasonal and perennial variations of atmospheric circulation patterns in Eocene marginal seas of mid-latitudes

Jorit Kniest (PhD)

Principal Investigators: Jacek Raddatz, Silke Voigt, Bodo Ahrens (Goethe University Frankfurt), Bernd Schöne (University of Mainz)

The overarching objective of the VeWA subproject A6 is to gain a better understanding of the nature and development of seasonality in the mid-latitudes under a warmer climate (Eocene Greenhouse). In this context, we are particularly interested in the interaction between the atmosphere and the oceans. For this reason, we aim to find evidence of seasonal to multi-year atmospheric circulation pattern in the marine environment. In order to accomplish this aim, we will employ fossil shallow-marine bivalves as proxy archives.

Still, there is little knowledge of how the current climate change may modulate seasonal and perennial variations of atmospheric circulation pattern. Therefore, the Eocene, as warmest period during the Cenozoic, might serve well as an analogue for the development of seasonality in the future.

Our investigations will mainly focus on marginal seas. In contrast to the open ocean, marginal seas exhibit faster response times to short-term climate variations (such as temperature), making them a superb system for investigating seasonality. Moreover, these areas represent a sensitive intersection between the terrestrial and marine environment, recording also changes in the hydrological cycle.

To investigate the paleo-climate conditions, we will reconstruct different environmental parameters, such as sea-surface-temperature (SST) and the fresh water input. To achieve this, we will utilize a variety of different geochemical proxies, such as Element/Ca ratios (e.g. Mg/Ca, Sr/Ca, Na/Ca, Ba/Ca), stable oxygen and carbon isotopes (δ18O, δ13C), as well as, the newly developed method of “clumped isotopes” (∆47, ∆48).

As proxy-archives we will use the skeletal hard parts of fossil bivalve. This taxon includes certain advantages for seasonality reconstruction. Bivalves construct their shells from separate layers, called growth increments. Each of these increment represent a certain amount of time. The time embodied within one increment can differ from a daily to annual base, depending on the species and the habitat. Sampling the particular increments generates a chronological record with a high temporal resolution, ideal for the reconstruction of seasonal variations.


Goethe University Frankfurt
PD. Dr. Jacek Raddatz:
Prof. Dr. Silke Voigt:
Prof. Dr. Bodo Ahrens:

Johannes Gutenberg University Mainz
Prof. Dr. Bernd Schöne: