Neotectonics, drainage and sedimentation in central Greece: insights into coastal reservoir geometries in syn-rift sequences

Abstract

Abstract The modern analogue of Greek environments was used to provide insights into the prediction of coastal syn-rift architectures. Sediment flux into rift basins reflects the drainage response to slope changes induced by normal faulting. The present day Greek drainage network reflects syn-rift modification of catchments draining the Alpine-Hellenide mountain chain. On a local scale, drainage around individual fault blocks commonly exploits transfer zones. Uplift and cannibalization of earlier sequences in the footwall of new normal faults also has a marked effect on sediment dispersal. Thus, consideration of catchment areas and their evolution offers an improved understanding of potential reservoir distribution and volumetrics within the stratigraphy of any given basin. Quantitative data on modern fault displacements and on rates of climatically forced, sea- and lake-level changes allow the prediction of relative base-level change at different localities around a half-graben or graben. Maximum rates of tectonic subsidence exceed all but the most rapid rates of glacio-eustatic sea-level fall (such as have occurred in the late Pleistocene). These data indicate it is inappropriate to apply, without some modification, sequence stratigraphic models that have been developed from areas with relatively simple subsidence histories (e.g. post-rift megasequences on passive margins) to syn-rift successions. Spatial variation in subsidence/uplift rates around rift basins is clearly demonstrated in central Greece, where coastal half-grabens show the resulting spatial and temporal distribution of systems tracts and sequence boundaries, and stratal geometries developed on a parasequence and sequence scale. Broad patterns of sequence stacking in deltaic and paralic facies are shown to be predictable, despite the apparent complexity of syn-rift successions. The fundamental control upon differential subsidence is the displacement history on individual normal fault segments. Patterns of relative base-level change and predictable sequence architectures are therefore scaled to the length of the fault segment.