[19-1] - KEYNOTE - The long-term relationship between sea-level change and sedimentation
Abstract: Sea-level rise (SLR) is one of the most important consequences of global warming and carries significant repercussions on coastal human settlements and natural ecosystems. Global SLR research aims at solving the so-called “sea-level budget” over the last few glacial-interglacial cycles. Gl...
| Main Authors: | , |
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| Format: | Article in Journal/Newspaper |
| Language: | unknown |
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Underline Science Inc.
2021
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| Online Access: | https://dx.doi.org/10.48448/wrdb-ag74 https://underline.io/lecture/33914-19-1---keynote---the-long-term-relationship-between-sea-level-change-and-sedimentation |
| Summary: | Abstract: Sea-level rise (SLR) is one of the most important consequences of global warming and carries significant repercussions on coastal human settlements and natural ecosystems. Global SLR research aims at solving the so-called “sea-level budget” over the last few glacial-interglacial cycles. Global-scale research efforts then provide the forcing and boundary conditions for regional-scale glacial- and hydro-isostatic adjustment (GIA) modelling. At that scale, sediment isostasy an compaction (SIC) becomes an important additional factor that has to be implemented in the modelling, through data intake and adapted algorithms. Regional sedimentation varied greatly in rates and amounts and locations between glacial and interglacial times, partly controlled by SLR and GIA movements but also independently. By accounting for sedimentation through the combination of mapping knowledge (data assimilation) and deterministic geophysical modeling, the magnitude of local SIC vs. regional GIA patterns can be revealed. In this work the contribution of GIA-driven RSL changes in drawing the architecture of stratigraphic sections is investigated by means of a novel numerical modeling approach. The latter consists in the full coupling between a GIA model, which is based on the Sea Level Equation, and two sedimentation models that are based, respectively, on (i) fuzzy logic and on (ii) the numerical solution of the heat transfer (diffusion) equation. Among the several variables that regulate marine sedimentation, changes in bathymetry and distance from shore and ice-sheet margin are directly linked to the gravitationally self-consistent RSL changes that are driven by GIA. The latter is also influenced by the load of the sediments that contribute to solid Earth and gravitational perturbations. The proposed algorithm, therefore, handles the biunivocal relationship between RSL changes and sediment loading in a synergistic manner. The model is used here to reconstruct the last two glacial-interglacial transitions and highlight the differences in the North Sea (intermediate field), Adriatic Sea (ice distal) and Ross Sea (ice proximal). Preliminary results show that the reconstructed ice-proximal stratigraphic sections, either based on fuzzy logic or diffusion, are significantly affected by the GIA process and that the eustatic approximation should be discarded. Also, SIC is currrently causing local subsidence and erosion in the proximity of river mouths where modern sedimentation rates cannot keep pace with SLR. This is a significant result for our understanding of centennial-millennial coastal plain development and habitat evolution, and for evaluating anthropogenic vs. natural sedimentation. Authors:* Stocchi P.* |
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