Sediment flux, depositional processes and architecture of a fault-bounded, base-of-slope submarine fan: Corinth Rift, Greece

Project highlights: Novel acquisition of high resolution geophysics, multi-beam bathymetry, side-scan sonar and seabed sampling data on a footwall-derived, base-of-slope submarine fan in a seismically-active rift basin; linked to new IODP borehole stratigraphic data; working as part of a wider international, collaborative project; key outputs will be high impact papers on high resolution depositional architectures and sediment flux across a rift margin

The problem: In rift basins, clastic submarine fans and aprons deposited adjacent to the active basin-bounding fault offer a physical record of the sedimentary and stratigraphic response to syn-depositional fault activity and to palaeoenvironmental changes. The starting hypothesis of this project is that rift structure controls deep-water sediment location, routing and the arrangement of depositional elements along sediment transport pathways, whilst environmental factors largely determine sediment transport process and stratigraphic cyclicity.

Previous outcrop studies that detail sedimentary facies and architectures have targeted the bedload-dominated systems of footwall-derived fan delta systems and associated axial turbidite sand fairways (e.g. Henstra et al, 2016; Barrett et al, 2019; Cullen et al, 2019). Studies of Late Quaternary systems that use seismic-reflection profiles combined with shallow drill cores have been focused on lakes in the East African Rift System (e.g. Lyons et al, 2011).

What has been lacking is a study locale in an active rift with a base-of-slope fan rich in suspension load, with the opportunity to collect a combination of seabed geomorphological and sample data, and high resolution (multi-channel) seismic-reflection data, in an area with deep drill cores. These integrated data provide a high resolution age model and constraint of depositional conditions throughout the imaged stratigraphy, and enable quantification of the response of sediment transport process, sediment volumes, facies, and depositional architectures to external environmental and tectonic variables.

Objectives: 1) To image and map submarine fault-scarp canyons, channels, lobes and the range of gravity flow deposits of the present day Sithas base-of-slope fan. 2) To resolve the stratigraphic architecture and sedimentology of the Sithas fan over the last 250 kyr (two major climate cycles). 3) To investigate how depositional architectures reflect local fault geometries and normal fault displacements. 4) To evaluate the impact of climate, sea- and lake-level variations and hinterland vegetational changes on deep-water deposition, utilising high resolution chronological and multiproxy environmental studies from IODP 381 cores. 5) To quantify the relative contribution of rift-margin fault processes and palaeoenvironmental changes in determining sediment flux onto (and beyond) the deep-water fan on 103-105 yr timescales.