Analogue modelling of the controls on the selective influence of pre-existing shear zones during rifting: Research stay at Helmholtz Laboratory for Tectonic Modelling (HelTec), GFZ Potsdam, Germany
I am a PhD student in the Basin and Reservoir Studies Group, Department of Earth Sciences, University of Bergen. My PhD research is a part of the SYNRIFTS (Syn-Rift Plays: Outcrop Analogues and Subsurface Applications) project, which is aimed at investigating how tectonic (evolving rift structures) and non-tectonic (e.g. climate, sediment supply, base level changes) factors influence the geometry and distribution of shallow marine and deep-water reservoirs in rift settings. Specifically, my research focuses on constraining the structural evolution of normal fault networks on and around the Utsira High, North Sea, and elucidate on the controls on the development of these network, using high quality wellbore-calibrated 3D seismic reflection dataset.
Results from my ongoing research and several other field-, seismic-, numerical- and analogue-based studies have revealed that pre-existing weak zones (such as shear zones) can induce mechanical, rheological, and even lithological heterogeneities that may influence the development and evolution of later rift-related normal fault networks. The reactivation of pre-existing weak zones and the consequent influence on rift faults is strongly dependent on the orientation of such zone relative to the maximum principal stress orientation. However, observations from recent studies show that while some shear zones may influence the geometry and growth of subsequent rift faults, others do not (despite being oriented at an angle to the maximum principal stress orientation that should ideally favour reactivation), therefore highlighting the selective influence of pre-existing weak zones on evolving rift fault network. These observations have led to suggestions that besides orientation, other factors such as the shear zone thickness, geometry, dip, and depth of occurrence may impose significance controls on the observed selective influence. However, the extent to which these other factors controls the influence of pre-existing weaknesses during rifting has not been systematically investigated, and therefore poorly understood.
To address the aforementioned knowledge gap, I contacted Dr. Matthias Rosenau who is in-charge of the Helmholtz Laboratory for Tectonic Modelling (HelTec) at GFZ, Potsdam. He was happy to collaborate, and consequently invited me as Guest Researcher to the Analogue modelling lab where I carried out experimental models to simulate rift-style deformation process in the presence of pre-existing basement weak zone. Thanks to part funding from DEEP, I was able to visit and work in the HelTec Lab for two months. The results of this research stay will form a part of my PhD thesis. I am very grateful to DEEP for the opportunity to not only visit an excellent laboratory in Potsdam, but also the opportunity to expand my skillset and academic network.
- by Edoseghe Edwin Osagiede