Diachronism of Pleistocene river terrace formation: Deciphering an inherent component of fluvial systems using high-resolution luminescence dating of terrace sediments in the Regnitz catchment (Upper Franconia, Germany)

• Applicant: Dr. Thomas Kolb
• Subject Area: Physical Geography
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 558956588

The concept of an asynchronous evolution of fluvial systems, formalized among others by S.A. Schumm, is a long accepted paradigm of fluvial morphodynamics. In the practice of fluvial-geomorphological research, however, it has so far led a rather astonishing shadowy existence. In the field of paleo-environmental research, this is evident, for example, in studies aiming at dating Pleistocene fluvial terraces in order to provide a temporal framework for reconstructing paleo-environmental conditions. Frequently, numerical dating is restricted to a single location that is supposed to be exemplary for the respective terrace level. Local dating results are then obtained for this site, from which "THE age" of the river terrace is inferred by way of a generalizing interpretation. With respect to the concept of asynchrony of fluvial reactions to environmental changes, such an approach seems to be problematic. Following the concept of an asynchronous evolution of fluvial systems, our project is based on the research-guiding hypothesis that the formation of Pleistocene river terraces is subject to a process-immanent diachronism. This diachronism is the result of an asynchronous and complex fluvial morphodynamics along the longitudinal river profile and is reflected in a diachronism of luminescence ages that can be determined for sediments of the respective terrace level at different locations. The central aim of our project is a systematic investigation whether it is possible to detect a diachronism of fluvial terrace formation by applying state-of-the-art techniques of luminescence dating to terrace sediments. The samples to be investigated originate from two fluvial terraces of supposed Wuermian (Weichselian) age located in the valley of the river Regnitz, one of the most important tributaries of the river Main. Thus, our project aims at a systematic investigation of the principal possibilities and limitations of luminescence dating methods with respect to the identification of response times in fluvial systems. The findings obtained in the project will have considerable relevance for the use of river terraces as climate and landscape archives for paleo-environmental research as well as for the temporal interpretation of environmental proxy data. The establishment of a high-resolution chronology will allow to make a valuable contribution to a better understanding of the Middle to Late Pleistocene landscape evolution in an important part of the Main River system. Furthermore, the project aims at promoting a close exchange between empirically based research in the field and computer-based landscape modeling. For this purpose, all acquired data will be made publicly available in a database, which will take into account the special requirements of landscape evolution modeling. This provides the opportunity to establish the study area as an important reference area for the validation and calibration of computer-based landscape evolution models.

• DFG Programme: Research Grants