Controls on the Evolution and Character of Siliciclastic Deep-Water Syn-Rift Depositional Systems

Ancient deep-water syn-rift systems provide a record of complicated interactions between
changing sediment supply from multiple input points, relative base level changes, and evolving
fault-related topography. Existing conceptual models have struggled to address stratigraphic
variability at fine spatiotemporal scales. Outcrop investigations can address this scale gap,
although exhumed systems are rare or often complicated by structural inversion. Here, the
stratigraphic architecture of the Early-Mid Pleistocene West Xylokastro Fault Block (Corinth
Rift, Greece) is documented using mapping, photogrammetric models, and an onshore
research borehole to establish an integrated palaeoenvironmental and tectonostratigraphic
evolution in a rare example of an exhumed deep-water syn-rift system.

The results highlight substantial heterogeneity across a range of scales. Coeval transverse
mass-wasting deposits impact the evolution of axial depositional systems through topographic
forcing not captured in existing models. Structurally-induced bathymetry drives development
of transient sediment bypass-dominated zones over ramps, and sediment accumulation in
intra-basinal lows. Spatially, fan-apron systems pass into laterally confined channel systems
over short distances (1–2km). The steep, short nature of onshore catchments and shelves
makes this syn-rift system sensitive to changes in sediment supply from onshore catchments.
Vegetation changes, recorded from palynological analysis of the research borehole, are
integrated with magnetostratigraphic chronology and may be coherent with climate variability
dictating sediment supply changes, including the development of laterally extensive
mudstones. Basin physiography also permitted substantial quantities of coarse-grained
material to be delivered, generating a spectrum of coarse-grained gravity flow deposits. The
study provides rare examples of bed- to meso-scale architectures preserved by these flows
within a constrained palaeogeographic context.

The study updates existing conceptual models for the physiographic, climatic, depositional,
and structural evolution of deep-water syn-rift systems. The thesis also highlights the
challenges in characterising syn-rift deposits and provides quantitative data to aid
understanding of tectono-stratigraphic controls and reduce uncertainty in other syn-rift
systems.