Unravelling a fault-related footwall canyon feature along the Roer Valley Graben System, the Netherlands

The sedimentary basin fill of the Cenozoic Roer Valley Graben System (the Netherlands) has gone through multiple phases of tectonic deformation during the Alpine orogeny, resulting in a variety of extensional and compressional structures, syn-tectonic sedimentary features and a complex and multidirectional fault pattern. The characteristics of these features, such as lithological properties, associated faults and their geometries, are crucial in geological investigations that focus on energy transition studies and/or water management. The present study seeks to enhance the geological understanding of a complex syn- and post-kinematic sedimentary feature, resembling a canyon-shaped collapse structure that formed on a relay ramp along the northern graben shoulder. Particular emphasis will be on methodology, mapping results and understanding the role of inherited faults on its development.

Since the late twentieth century, the Geological Survey of the Netherlands (GDN-TNO) has played an important role in advancing scientific understanding of the country’s subsurface geology. A major accomplishment of the GDN-TNO is the creation of comprehensive, country-wide subsurface models, using numerous 2D and 3D seismic surveys of various vintages as well as a substantial number of exploratory wells and more recently the results of the SCAN (Seismic Campaign for Accelerating Geothermal Energy) program.

Past and recent systematic inspection of this legacy data of the GDN enables us to examine both the geometry (i.e. the shape and spatial arrangement) and mechanisms of faults and associated specific sedimentary features, such as hanging-wall collapse and accretionary channel infill structures, as well as a plausible sedimentary wedge downslope of the hanging wall. Combining this with the results of our subsurface geological models, we present the potential relevance of inherited tectonics and fault reactivation on the development of these syn- and post-kinematic sedimentary features in the subsurface of the Netherlands. 2D seismic data may not always be sufficient to understand the fault orientation and length. To address these challenges and improve the accuracy of our geological modelling approach, we will incorporate and present our findings from adjacent 3D seismic datasets combined with conceptualized tectonic diagrams and real world analogues.