|
Rift Structure: Models and Observations |
1 The Research School of Geological and Geophysical Sciences, Birkbeck and University College London, University of London, Gower Street, London WC1E 6BT, UK
2 Department of Geology, University of Manchester, Manchester M13 9PL, UK
Structural and diagenetic studies at several localities along the strike of a single fault segment within the eastern Gulf of Corinth show that deformation and diagenetic textures vary along-strike. Uplifted phreatic carbonate cements fill fractures within footwall localities in the centre of the fault segment, whereas, at the termination of the fault segment within the Psatha interbasin transfer zone, fractures filled with vadose calcite cements are associated with an extensive karst system. A small-scale offset between two fault strands along the centre of the fault segment within the Asprokambos intrabasin transfer zone is also dominated by fracture-filling phreatic cements. Fractures filled with phreatic cements exhibit crack-seal textures and low porosities, and formed in fluid-saturated conditions below the water table. In contrast, fractures filled with vadose cements have asymmetric cement textures associated with connected karstic porosity, and formed above the water table. The variations in deformation and diagenesis result from decreasing displacement and footwall uplift towards the ends of the fault segment giving differential uplift across the water table/sea level. Variation in fracture styles and diagenetic textures have been correlated with the position of sample sites along the fault segment. It is therefore possible to use outcrop studies of deformation and diagenetic textures from different portions of fault segments to produce simple predictive models to aid hydrocarbon exploration and production strategies.
