Microsedimentology of ice stream tills from the Eastern Alps, Austria – a new perspective on till microstructures
Bibliographic record
Abstract
This study of tills from the Eastern Alps, Austria, illustrates the insights obtained using microsedimentology on subglacial tills in the context of palaeogeographical reconstructions of glacier advances. Investigations of several sites with tills derived from both local glaciers and the ice‐sheet streaming of the Inn Glacier during the Last Glacial Maximum and its termination reveal a detailed picture of subglacial sedimentology that provides evidence of soft sediment subglacial deformation under polythermal conditions. All the tills exhibit microstructures that are proxy evidence of significant changes in till rheology. The tills originate from multiple sources, incorporating older tills and other deposits picked up by the subglacial deformation within a polythermal but dominantly warm temperate subglacial thermal regime. The analyses of till microstructures reveal a direct relationship between basal ice strain conditions and their development. A hypothesis is derived, from the various microstructures observed in these Austrian tills formed under soft sediment deforming basal ice conditions, that suggests that with basal thermal changes and fluctuations in clay content, pore‐water content and pressure, microstructures form in a non‐random manner. It is postulated that in clay‐deficient sediments, edge‐to‐edge events are most likely to occur first; and where clay content increases, grain stacks, rotation structures, deformation bands and, finally, shear zones are likely to evolve in an approximate sequential manner. After repeated transport, emplacement, reworking and, probably, further shearing and deformation events, an emplaced ‘till’, as observed in these Austrian tills, will form that carries most, if not all of these microstructures, in varying percentages. Finally, the impact of the Inn Glacier Ice Stream on these tills is not easily detected and/or differentiated, but indications of high pore water and probable dilatant events leading to reductions in the number of edge‐to‐edge events point to the impact of fast or thick ice upon these subglacial tills.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 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".