Incised-valley morphologies and sedimentary-fills within the inner shelf of the northern Bay of Biscay

TL;DR

This study synthesizes data on incised-valleys in the inner shelf of the Bay of Biscay, highlighting how tectonics, lithology, and bedrock morphology influence valley shapes and sedimentary fills based on seismic and coring data.

Contribution

It provides a new synthesis emphasizing the role of bedrock morphology and tectonics in shaping incised-valley features and sedimentation patterns in the Bay of Biscay.

Findings

Valley morphology is strongly controlled by tectonics and lithology.

Pleistocene sedimentary cover is thin and discontinuous.

Valley fills vary due to bedrock morphology affecting sediment transport.

Abstract

This study is a first synthesis focused on incised-valleys located within the inner shelf of the Bay of Biscay. It is based on previously published results obtained during recent seismic surveys and coring campaigns. The morphology of the valleys appears to be strongly controlled by tectonics and lithology. The Pleistocene sedimentary cover of the shelf is very thin and discontinuous with a maximum thickness ranging between 30 and 40 m in incised-valley fills. Thus the incised bedrock morphology plays a key-role by controlling hydrodynamics and related sediment transport and deposition that explains some variations of those incised-valley fills with respect to the previously published general models.