Weathering regime and geochemical conditions in a polar desert environment, Haughton impact structure region, Devon Island, Canada
Bibliographic record
Abstract
This study examines the physical and geochemical properties of near-surface sediments, as well as the geochemical and stable O–H–C isotope composition of (ground)surface waters in and around the Haughton impact structure region (Devon Island, Nunavut) to determine the types of weathering (mechanical, (bio)chemical) and their relative contribution in this polar desert environment. The surface sediments collected from the Allen Bay and Thumb Mountain formations surrounding the impact crater are dominated by sand-sized particles; whereas the impact melt breccias inside the crater have a greater abundance of silt-sized particles. The subsurface sediments in the Allen Bay formation show a near equal amount of sand- and silt-sized particles. However, the micromorphologies of the sand-sized particles collected at the surface revealed that these grains, irrespective of the local geology, were heavily fractured. By contrast, fractures and rounded pits are observed on the surface of the sand grains located within the active layer; whereas those located just above the permafrost table have only rounded cavities on their surface. The (ground)waters also show variations in their solute concentration with depth; the highest concentrations being found in the groundwaters near the top of permafrost. Taken together, these observations suggest that there is a progressive evolution from a mechanically dominated weathering regime near the surface, to increasing chemical weathering with depth. The transition from mechanical weathering near the surface to increasing chemical weathering with depth can be attributed to the decreasing frequency and intensity of mechanical weathering processes (i.e., frost action, wetting–drying, thermal dilation) with depth, and to the presence of permafrost, which allows a greater availability of water for chemical aqueous reactions at the base of the active layer.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| 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".