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Gravitational, erosional, sedimentary, and volcanic processes on the submarine environment of ocean volcanic islands
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Abstract(s)
Volcanic ocean islands are shaped by a complex interplay of volcanic, erosional, sedimentary, and marine processes. While their subaerial evolution is well-documented, their submarine portions remain underexplored, particularly shallow-water areas that hold key insights into island development. This PhD research investigates the post-volcanism evolution of insular shelves by integrating onshore and offshore datasets from two case studies: Porto Santo (Madeira Archipelago) and Corvo (Azores Archipelago). These islands, despite both being of volcanic origin, exhibit distinct geological histories, oceanographic conditions, and morphological characteristics, making them ideal for comparative analysis.
A multidisciplinary approach was employed, combining high-resolution bathymetric surveys, seismic reflection profiling, sediment sampling, and geomorphological analysis. Porto Santo's southern insular shelf was studied using existing geophysical datasets and sediment samples, while Corvo's submarine environment was newly mapped through targeted oceanographic campaigns. Data processing involved acoustic imaging, stratigraphic interpretation, and sedimentological assessments to reconstruct the evolution of their submarine landscapes.
The results indicate that both islands are shaped by a combination of subaerial and wave-induced erosion, sediment deposition, and gravitational mass-wasting processes at different magnitudes. Porto Santo has reached a mature stage of development, featuring an extensive bioclastic sandy beach that transitions into depositional bodies on the shelf, dominated by present-day carbonate factory. In contrast, Corvo exhibits a rugged landscape, characterized by steep cliffs and a high-energy marine environment shelf dominated by mass-wasting deposits and terrigenous depositional bodies. The comparative analysis underscores the influence of sea-level fluctuations, island age, and oceanographic dynamics in controlling shelf morphology and sedimentary architecture.
These findings enhance our understanding of volcanic island evolution and provide valuable insights into coastal stability, marine resource management, and natural hazard assessment. The research results contribute to sustainable development initiatives, particularly in mitigating erosion risks, managing marine aggregates, and preserving marine ecosystems.
Description
Keywords
Volcanic insular shelves Post-volcanism evolution Marine erosion Sedimentary dynamics Mass-wasting processes Plataformas insulares vulcânicas Evolução pós-vulcanismo Erosão marinha Dinâmica sedimentar Processos gravitacionais