Fault and fluid interaction in a rifted margin: integrated study of calcite-sealed fault-related structures (southern Corinth margin)

Abstract

Abstract This work integrates microstructural, petrologic, microthermometric and geochemical analysis of calcite-sealed fault-related structures of the major faults of the southern margin of the Corinth rift (Greece). It draws attention to the main deformational processes and fault–fluid interaction in fault zones along the whole margin. Data analysed come from the compact breccia located immediately adjacent to major fault planes. Samples were collected at different positions alongside different faults juxtaposing synrift continental deposits (hanging wall) against the prerift Pindus limestones (footwall). This implies hectometric fault displacements and that the fault zones have recorded a relatively long evolution of deformation. Our study identifies four main deformation features common to all studied faults: calcite cemented breccia, extensional veins, shear veins and fault slip surfaces. The integrated data analysis shows that deformation structures and fault rocks that coexist in the same outcrop formed at different depths and times. During inferred upward fault propagation, the style of deformation evolved from distributed (brecciation) to localized (slip surfaces) and from a closed system with fluid–rock equilibrium during brecciation to a more open one with limited influx of meteoric water during extensional and shear fracturing. This implies relative uplift of the footwall during fault propagation and fault interaction with different water aquifers as the fault propagates upwards. The results demonstrate similar fault evolution and fault–fluid interaction through the entire rifted margin and during the whole rifting period.