Early-Stage Ground Modelling in a Mediterranean Shelf Margin: a Sequence Stratigraphic Approach

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4. Early-Stage Ground Modelling in a Mediterranean Shelf Margin: a Sequence Stratigraphic Approach

Quaternary stratigraphy of the Mediterranean shelves is largely controlled by glacial-interglacial eustatic cycles that defined the volume of sediment available for deposition and controlled sediment accommodation space, geometry and thickness of the soil units.  To develop an early stage integrated ground model for a floating windfarm site in the southern Adriatic we adopt a simple sequence stratigraphic approach aiming to link shallow geophysical and geotechnical data into a coherent framework, allowing the distinction of mappable wedges interpreted to represent the depositional signature of distinct phases within sea-level cycles. Starting from a seismostratigraphic analysis of the site based on a dense grid of SBP and UHR data, we define three main fourth order (10⁴ years) stratigraphic units bounded by erosional surfaces, each representing a full eustatic cycle. Individual units are in turn divided into separate sub-units encompassing all deposits accumulating during one phase of relative sea-level and preserved between specific primary chronostratigraphic surfaces.  The stratigraphic process-response model pyBarSim, which uses event deposition to simulate stratigraphic response to changes in sea level and sediment supply, is used to qualitatively validate the results and favour the dissemination of specific stratigraphic concepts to non-specialists. Geotechnical data, including seabed CPTs and shallow vibrocore sampling, allow the ground-truthing of the stratigraphy and the definition of soil types unique to each main unit. Vertical and lateral trends in soil characteristics are found to correlate to sub-units whose depositional pattern was primarily controlled by the sea level cyclicity; this predictable behaviour facilitates a preliminary estimation of geotechnical properties away from CPT control points and an improved understanding of the geohazard processes.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

4 - Ground models