Lithosphere and upper-mantle structure of the southern Baltic Sea estimated from modelling relative sea-level data with glacial isostatic adjustment
Bibliographic record
Abstract
Abstract. During the last glacial maximum, a large ice sheet covered Scandinavia, and the Earth's surface was depressed by several 100 m. Beyond the limit of this Fennoscandian ice sheet, mass redistribution in the upper mantle led to the development of peripheral bulges around the glaciated region. These once uplifted areas subside since the begin of deglaciation due to the viscoelastic behavior of the mantle. Parts of this subsiding region are located in northern central Europe in the coastal parts of Denmark, Germany and Poland. We analyze relative sea-level (RSL) data of these regions to determine the lithospheric thickness and radial mantle viscosity structure for distinct regional RSL subsets. We load a one-dimensional Maxwell-viscoelastic earth model with a global ice-load history model of the last glaciation. We test two commonly used ice histories, RSES from the Australian National University and Ice-5G from the University of Toronto. Our results indicate that the lithospheric thickness varies, depending on the ice model used, between 60 and 160 km. The lowest values are found in the Oslo Graben area and the western German Baltic Sea coast. In between, thickness increases by at least 30 km tracing the Fyn High. In Poland, lithospheric thickness values up to 160 km are reached. However, the latter values are not well constrained due to a low number of RSL data from the Polish area. Upper-mantle viscosity is found to bracket [2–7] × 1020 Pa s when using Ice-5G. Employing RSES much higher values of 2 × 1021 Pa s yield for the southern Baltic Sea, which suggests a revision of this ice-model version. We confirm that the lower-mantle viscosity in Fennoscandia can only be poorly resolved. The lithospheric structure inferred partly supports structural features of regional and global lithosphere models based on thermal or seismological data. While there is agreement in eastern Europe and southwest Sweden, the structure in an area from south of Norway to northern Germany shows large discrepancies for two of the tested models. It thus remains challenging to sufficiently determine the Fyn High as seen with seismics with the help of glacial isostatic adjustment modelling.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".