Channel and Lobe Interaction With Basin Floor Topography in Deep Water Rift Basins – Plio-Pleistocene Syn-Rift of the Corinth Rift, Greece

Abstract

Deep water sedimentary systems in rift basins are largely affected by changes in hydraulic conditions triggered by modifications in the basin floor topography due to the evolution of normal faults. The resulting geometries of the depositional bodies and their stacking patterns are not always clearly resolved in seismic imaging. In order to investigate the interactions between channels and lobes under the influence of extensional tectonics this study is based on seismic-scale exposures of the Plio-Pleistocene syn-rift deep water depositional systems exposed in the Corinth Rift, Greece. The integration of detailed mapping and sedimentary logging with digital techniques (LiDAR, photogrammetry and UAV mapping) results in a kilometers-scale digital outcrop model, combining information of facies composition, architectural elements and rock body geometry, sedimentary stacking patterns and tectonic structures. The outcome of this study has wide applicability for reservoir characterization and grain-size distribution in deep water deposits in rift basins.

The studied interval comprises several mudstone-dominated and sandstone-dominated units of sheet geometry punctuated by the occurrence of coarse-grained mounded bodies in a ~500 m thick succession. The sandstone-dominated sheets are composed of shallow channels 0.5 to 3 m thick and up to 70 m of lateral extent. The mounded bodies vary in thickness from 5 to 20 m and can extend laterally for more than 1.5 km. They consist of vertically stacked conglomerate beds up to 2 m thick and sandstone lenses of few cm in thickness. Clear differences in clast composition between the various deep water sedimentary units allows for establishing possible source areas within the rift basin.

The depositional environment was characterized by an axial subaqueous channel complex that was sourced by various transverse entry points linked to rift shoulder fan deltas (the Kefalari, Kyllini, Mavro, Evrostini and Illias deltas). Fault activity at the basin floor controlled the transport direction of the sedimentary system by routing the sediment-laden flows and caused gravitational instabilities. The development of slumping and sliding processes subsequently diverted the transport patterns of channelized units, also affecting their stacking patterns.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018