Continental Margin Process Analysis, Structures & Stratigraphy
Influence of lithosphere extension and mantle flow processes on basement and sedimentary architecture of the Central South Atlantic margins.
Supervisors: Dr Marta Pérez-Gussinyé, Prof Jason Phipps Morgan, Dr Graeme Eagles, Prof Peter Burgess
Extension of the continental lithosphere portrays a wide range of tectonic styles depending on factors such as initial lithospheric rheology and the velocity of extension. In addition, plume-linked asthenosphere flow may exert additional geodynamic controls on the vertical motions and syn- and post-rift magmatism along passive margins. Understanding how and why these different tectonic styles developed is a key element for the prediction of petroleum systems at continental margins. The Central South Atlantic margins present an ideal natural laboratory to study the effects of rheology, rift speed, and asthenosphere flow on the styles of rifting and post-rift margin evolution. For example, from South to North along the South American margin, extension developed first on weak mobile lithosphere, in the Espírito Santo, Campos and Santos basins and then it initiated on cratonic one in the Camamu and Jacuipe basins. Understanding how these different rheologies acted with variations to extension velocity is a very important element in predicting the petroleum systems that are subject of ongoing exploration along these continental margins. Additionally, plume-linked asthenospheric flow may have been important in shaping the post-rift evolution of some segments of the margin. For example around the Rio de Janeiro segment, the Trindade Plume-linked asthenosphere flow may have influenced the post-rift evolution of this margin.
This PhD project will use 3-D and 2-D dynamic numerical models to investigate how rheology, extension speed, and asthenosphere flow influence margin tectonic style, subsidence, heat flow history and hence petroleum system evolution. Modelling will be constrained by seismic data. Extension speeds and basin configurations in our modelling experiments will be constrained by velocities and geometries from plate kinematic models of the South Atlantic opening (from PhD1). Our modelling will incorporate the syn‐ and post‐ rift sedimentary cover so that the impact of extensional styles on sediment architecture during the whole margin history can be analyzed. Work will include the post-rift phase where the influences of evolving ridge push forces and lithosphere and plume-asthenosphere-subduction-linked dynamic topography effects on margin and sedimentary architecture will be analysed.
Specific deliverables of the PhD project are:
- Geodynamic simulations of lithospheric deformation, vertical margin motion, and sedimentation during rifting, break-up, and drift of selected South Atlantic conjugate margins
- Classification of lithospheric deformation styles according to extension speed, initial rheology, asthenosphere-linked effects, and amount of sedimentation through time
- Assessment of ridge push forces and their role in post-rift tectonic inversion in selected transects of the South Atlantic
| Parallel MATLAB-based 3D viscous flow and temperature model beneath offset Mid-Atlantic Ridge segments.