3-D Structure and Evolution of Passive Margin Salt Systems: Insights from Analogue Modeling and Optical Deformation Analysis

Csaba Krezsek, Juergen Adam, Steve King, and Djordje Grujic
Dalhousie University, Halifax, NS

Deformation associated with gravity gliding on a viscous salt substrate has previously been investigated by geophysical surveys and analogue and numerical modeling. 2D basinward evolution of linked coeval extensional – compressional systems is fairly well understood. However, few studies have addressed the 3D evolution of complex grabens and related fault systems.

We apply scaled analogue experiments of brittle-ductile systems and particle imaging velocimetry (PIV) to simulate passive margin salt and sedimentary basin tectonics. PIV is a high-resolution optical 3D deformation and surface flow monitoring technique and data analysis includes calculating incremental and finite values of subsidence, displacement and strain to quantify the space and time evolution of structures and sedimentation.

3D structural interpretation was performed with conventional seismic interpretation software using prepared sections from the physical models and PIV data to control fault interpretation. Several extensional and compressional subdomains were recognized in these systems.

Interpretation includes complex along-strike variability of structures, such as change of rollover dips and related “transfer” zones, highly variable and localized subsidence patterns, and complex late-stage collapse of rollover anticlines and diapirs. It is evident that an accurate analysis of these structures can only be completed through correct spatio-temporal monitoring provided by PIV data.

Our results give improved insights into the nature, variability and mechanics of brittle-ductile sedimentation/deformation coupling and its relation to the 3D development of sedimentary basins in presence of dynamic salt systems.