Toward quantifiable temperature reconstructions from bivalve shells

• Antragsteller: Professor Dr. Bernd R. Schöne
• Fachliche Zuordnung: Paläontologie
• Förderung: Förderung von 2012 bis 2016
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 221516699

Bivalve shells are becoming increasingly recognized as powerful tools for paleoclimate reconstructions. However, it still remains extremely challenging to obtain precise paleotemperature (T) data from this archive. The only well-accepted proxy for T in bivalves, 18O values (oxygen isotope ratios) is a dual proxy because it simultaneously informs about changes of T and the 18O value of the ambient water. To reconstruct precise T from 18Oshell, the 18Owater value (or salinity) must be known, which is rarely the case for ancient environments. Likewise shell growth rate is a dual proxy (T and food). Therefore, an essential and pressing question remains unanswered: How can we obtain quantifiable T data from shells of marine and brackish bivalves? The proposed study addresses this question with a multiproxy approach that combines various different (relatively) inexpensive paleothermometers which are suitable for high-resolution paleoclimatology. This includes the necessity to (1) refine existing T proxies (18Oshell, shell growth), and (2) rigorously test and verify less frequently applied T proxies (Sr/Ca, Bauwens’ model) through field and lab experiments. Since 18Oshell and shell growth are dual proxies, we will specifically explore potential proxies for the other main environmental factor, i.e., 18Owater (through D of the shell organic matrix) or salinity (Na/Cashell) in the case of 18Oshell, and food (crystal fabrics, 13Cshell) in the case of shell growth. Results of this study will significantly increase the robustness of this highly versatile climate archive.

• DFG-Verfahren: Sachbeihilfen