AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Normal Fault Relay Zone Geometries in the Early Gulf of Corinth Rift (Greece) and Its Application as a Hydrocarbon Exploration and Production Analogue
(1) School of Earth and Environment, University of Leeds, Leeds, United Kingdom.
Characterization of relay zone geometries is a critical aspect in the structural mapping of subsurface, fault-bound reservoirs. Geometries control stratigraphic juxtapositions and potential reservoir spill points. However, few outcrop examples of relay zones developed within multi-layered stratigraphies have been studied in detail. The onshore Gulf of Corinth presents a series of E-W oriented fault sets of Plio-Pleistocene age, with alluvial to deltaic syn-rift deposits within their hangingwall half graben depocentres. Detailed structural mapping north of Kalavryta in the northern Peloponnese has revealed that faults previously described as continuous entities are in fact composed of a series of smaller segments interacting through a variety of linkage geometries. The stratal architecture of the alluvial fan deposits provides a tool for constraining the sequence of sub-basin development in the hangingwalls to individual fault segments, as well as the linkage history of the larger fault sets. Integration of field and digital elevation data within a geomodelling environment has allowed the along-strike variation in displacement to be characterized, revealing the position of displacement minima associated with relay zones, as well as permitting the pre-rift basement topography to be estimated.
A combination of structural and sedimentological data suggests a three stage evolution of rifting in the area, previously thought to consist of a simple northwards progression of fault activity. Initially extension was dispersed across a wide area prior to localization onto the most southerly basin bounding fault set in the second stage of rifting. The associated increase in accommodation space allowed the progradation of a large alluvial fan across the area. The third stage of rifting sees the development of a number of half grabens as faults propagate up through pre-rift carbonate deposits and the overlying alluvial fan sediments. Deformation and relay zone geometries vary and are influenced by a number of both sedimentological and structural variables. By constraining and predicting the effect of these variables it may be possible to apply the deformation geometries observed here to areas of uncertainty within analagous exploration and production settings.