Controls on the long‐term downward transport of δ²H of water in a regionally extensive, two‐layered aquitard system
Bibliographic record
Abstract
Seven high‐resolution (0.3–0.6 m depth intervals), 1‐D vertical profiles of the δ²H of pore water were collected across a 300 km2 study area in southern Saskatchewan, Canada, to define the vertical controls on solute transport in a >120 m thick, two‐layered aquitard system. The 1‐D profiles were augmented with an existing δ²H profile collected from a previous study. The surficial aquitard in the area consists of Quaternary deposits (either glacial till or lacustrine deposits; 13 to 128 m thick) underlain by an upper Cretaceous claystone aquitard (80–110 m thick). The shape of the individual δ²H profiles and associated 1‐D transport modeling suggest diffusion is the regionally dominant vertical transport mechanism across the aquitards. The profile shape is controlled by the thickness of the Quaternary deposit and the δ²H value at the upper boundary, which coincides with the depth of the water table. The upper boundary δ²H value varies considerably across the area (−149‰ to −101‰), perhaps due to differences in local hydrological conditions (e.g., slope, aspect, infiltration) across the landscape. Modeling of all profiles shows the timing for till deposition and the timing of climate change during the Holocene are consistent across the area (∼30 ka and 7–10 ka before the present, respectively), corroborating other studies. This study provides insights into the hydrogeologic controls on solute transport in an aquitard system and associated geologic and climatic changes for a prairie region over the past 30 ka, and improves our understanding of initial and time‐dependent transport boundary conditions for the study of aquitards.
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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 | 0.000 | 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) | 0.000 | 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".