Continental Margin Process Analysis, Structures & Stratigraphy
Interaction of tectonic and gravity-driven deformation processes with deposition systems during syn-rift and post-rift sedimentary basin evolution.
Supervisors: Dr Jürgen Adam and Prof Peter Burgess
The tectono-stratigraphic evolution of sedimentary basins on rifted continental margins is complex, being strongly controlled by the interaction of tectonic processes, gravity-driven deformation, and a wide variety of sedimentary processes. One way to better understand how all these processes create strata and determine the evolution of petroleum system is to integrate numerical stratigraphic forward models with analogue experimental techniques.
Scaled 3D analogue experiments constrained by geological data and with high-resolution digital 3D deformation monitoring, are able to simulate fault localisation, linkage and displacement and resulting tectonic basin subsidence, including 1st order syn-kinematic sedimentation, with high spatial and temporal resolution. Royal Holloway is a world-leader in developing these techniques (Adam et. al, 2012; Adam & Kreszek, 2012, Adam & Salt Tectonics Group, 2008; Kreszek & Adam, 2007). However, such analogue experiments cannot simulate more complex observed stratal architectures such as fan and clinoform systems controlled by external factors like sea level and climate variations. Conversely, numerical stratigraphic modellers are able to simulate these more complex stratal geometries but currently lack the ability to incorporate sufficiently complex tectonic subsidence models and basin form histories. Given this, there is a need to integrate scaled 3D analogue experiments simulating tectonic basin formation with stratigraphic forward models to simulate different basin fill histories to provide a qualitative and quantitative understanding of the complex structural and stratal architectures and the feedback mechanisms that may control them.
The proposed PhD project will develop a new workflow to integrate numerical 3D stratigraphic forward modelling (SFM) techniques with basin-scale 3D analogue experiments for realistic simulation of depositional systems during syn-rift and early post-rift basin formation. The new workflow will be used to explore the impact of various tectonic, depositional and climatic conditions that control basin formation and fill on rifted margins.
The project will start with an existing prototype 2D stratigraphic forward model that simulates stratal architectures using a simple event-based sediment transport model. Sediment is transported as packages with a defined grain size population, using simple physically reasonable rules for erosion, transport and deposition, based on topographic gradient curvature and gradient thresholds. Development of the stratigraphic forward model will include an expansion to 3D (the 2D version is easily expandable to 3D as demonstrated by code in other models e.g. CarboCAT), addition of water flow calculations to allow better differentiation of fine and coarse-grained deposition, and improved visualization of model results. A workflow will then be developed to integrate output from the SFM and the analogue tectonic modelling. For incremental evolutionary stages of the basin (e.g. experiment stages), topographic surfaces derived from the analogue experiment data will be used as input to the SFM to define basin subsidence and bathymetry. For each discrete time interval, sediment volume, facies distribution as well as depositional and erosional pattern will be calculated by the SFM in response to this surface. The results will be scaled and recreated on the analogue experiment surface by deposition and removal of material via prototype automated mechanical sedimentation devices. During the subsequent time interval the experiment surface will further develop in response to the combined experiment deformation processes and the SFM sediment and erosion pattern. At the end of this time interval the new dynamic experiment topography will be scanned and transferred back to the SFM and the process repeated.
The new techniques will be tested by application to selected segments of the Central and South-Atlantic conjugate margins (or similar study areas agreed with partners). Results from this work will also support and aid benchmarking of sedimentation procedures in 2D/3D numerical simulation techniques of lithospheric deformation processes in projects 1 and 2. For example, stratigraphic forward model algorithms developed in this project will also be coupled with numerical models of lithospheric deformation.
Specific deliverables of PhD project 4 are:
- A prototype of a new 3D event-based siliciclastic stratigraphic forward model.
- Methods, equipment and experiment workflows for coupling of 3D analogue experiments and the 3D stratigraphic forward model to simulate basin-scale dynamic tectonic-depositional systems
- Interfaces between digital experiment output and FSM input.
- Workflows for integration of AM-FSM procedures including scaling properties relevant for geological processes in rift and passive margin basins.
- Proto-type devices for experiment sedimentation procedures based on FSM input data.
- Tectono-stratigraphic analysis, simulation and reconstruction of structural and stratal architectures during the syn-rift and post-rift evolution of selected basins on South Atlantic conjugate margins.