Source-to-Sink signal propagation in a coupled catchment-deep-sea fan system: the Sithas example from the Corinth Rift (Pleistocene, Greece)

Since the early 2000s, the development of the Source-to-Sink (S2S) approach improved the understanding of variations in the sedimentary signal and its controlling factors within coupled catchment-sedimentary system. However, S2S study remains difficult, as the data and time scales of the distinct compartments of the system may be incompatible, poorly resolved or even lacking. The combined quantification of sediment budget in both the catchment’ and sedimentary basin’s parts of the system is a way to address this problematic.

The aim of this study is (i) to jointly measure erosion and sediment deposition across an entire S2S system, and subsequently (ii) discuss the influencing factors and the mode of signal propagation. The study focuses on the system of Sithas (Corinth rift, Greece), where numerous geomorphologic markers (e.g., marine terraces) provide constrains to quantify eroded volumes, and a large offshore dataset is available to establish well-constrained sedimentary budget.

To achieve this, we updated an age model for the last 800 ka. We then restored the volumes of sediment eroded in the catchment and quantified the volumes of sediment deposited offshore to estimate fluxes of sediments from the source and the sink during the last 800 ka Quaternary climatic cycles. We also compared these results with a multi-regression empirical model estimating suspended sediment loads (BQART).

Erosion (source) and sediment (sink) fluxes have shown a gradual increase since 800 ka: from 3km³/Ma for the source and from 1. to 75. km³/Ma in the deep-sea fan (sink). This overall increasing trend is superimposed by cyclic variations, in both erosion and deposition signals. Significant increases in fluxes are observed over periods of around 12 ka every 120 ka (at circa 10, 120, 230 and 340 ka), which are followed by a progressive decrease. They coincide respectively with high sea levels according to the global eustatic curve (odd Marine Isotopic Stages). Surprisingly, the peaks of fluxes in deposition (sink) are preserved prior to the peaks of fluxes in erosion (source) with a time lag of around 30 ka. The comparison with BQART fluxes also shows the significant influence of the catchment size and the climatic factors such as temperature and precipitations in modulating the signal propagation.

These observations suggest that even for small, coupled catchment-deep sea fan system, the signal propagation is not straightforward, and thus deserves much more attention in future works.