The influence of tectonics on river terrace evolution in the Guadix/Baza Basin, Spain

River terraces are common features in landscapes around the world, created through the interaction of erosion and sedimentation processes. Although these terraces are widespread, many aspects of their formation and development remain unclear, especially regarding the mechanisms and conditions that control their evolution. The Guadix/Baza Basin in Andalusia, situated within the Granada UNESCO Geopark, offers a unique natural laboratory for studying these questions. Over time, this basin has undergone substantial geological transformations. Initially, it was a closed depression where sediments from the surrounding mountains accumulated. During the Middle to Late Pleistocene, a river capture event caused the basin to transform into an open river system, leading to the development of several generations of river terraces. These terraces are often associated with calcareous sinter formations found in deeply incised valleys. A key factor in the basin's evolution is its dynamic neotectonic activity. The area is characterized by a complex system of faults, with the Baza Fault acting as a major fault system dividing the research area into two distinct sub-basins.

The aim of our DFG-funded research project is to study the processes that influenced the evolution of the fluvial system after the river capture, with a particular focus on fluvial erosion dynamics. To reconstruct the development of terrace formation, luminescence dating is applied to terrace sediments, while U/Th dating is used for associated calcareous sinter formations. This combination allows the establishment of a chronostratigraphy, providing insights into the rates of erosion and the incision patterns of local rivers.

Our contribution will present an overview of the project’s objectives, outline the applied methods, and discuss initial results, including the first chronostratigraphy of the eastern Baza sub-basin. A key focus will be placed on the influence of tectonic activity on terrace formation and how these forces shaped the development of the regional river network. Preliminary findings suggest that tectonics played a significant role in terrace formation, influencing both the thickness and depositional patterns of sedimentary layers. This, in turn, has implications for the interpretation of dating results, as the tectonic setting directly affects the stratigraphic context and preservation of terrace sequences.

The study highlights the importance of integrating numerical laboratory results with empirical fieldwork. A comprehensive understanding of terrace evolution and sedimentary processes is only achievable when the specific tectonic framework of the study area is carefully considered.