Late surge glacial conditions on Bakaninbreen, Svalbard, and implications for surge termination
Bibliographic record
Abstract
Bakaninbreen is a polythermal glacier in southern Spitsbergen, Svalbard, that last surged between 1985 and 1995. Seismic reflection data were acquired during early quiescence in spring 1998, just upstream of the surge front. The results were combined with complementary ground‐penetrating radar data to investigate the glacial structure and basal conditions. We find no difference between the ice thickness values determined from the seismic and radar methods, suggesting that any layer of basal ice cannot be greater than ∼5 m thick. Interpretation of the amplitude of the seismic reflections indicates the presence of permafrost close to the glacier base. A thin layer of thawed deforming sediment separates the glacier from this underlying permafrost. In an area just upstream of the surge front the permafrost becomes discontinuous and may even be absent, the ice being underlain by 10–15 m of thawed sediments overlying deeper bedrock. High‐pressure water is believed to have been required to maintain the propagation of the surge, and this area of thawed sediment is interpreted as a route for that water to escape from the basal system. When the surge front passed over this thawed bed, the escaping water reduced the pressure in the subglacial hydraulic system, initiating the termination of the surge. Surge termination was therefore primarily controlled by the presurge permafrost distribution beneath the glacier, rather than any feature of the surge itself. This termination mechanism is probably limited to surges in polythermal glaciers, but the techniques used may have wider glaciological applications.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".