Mapping the Geometry and Lithostratigraphy of a Paleovalley with a Time-domain Electromagnetic Technique in an Area with Small Resistivity Contrasts, Groundbirch, British Columbia, Canada
Bibliographic record
Abstract
Abstract The purpose of this paper is to evaluate the effectiveness of large loop, ground-based, time-domain electromagnetic surveys for modeling of paleovalley geometry and valley fills as a basis for determining groundwater potential. The electromagnetic (EM) survey was successful, despite limited resistivity contrast between adjacent valley-fill units, as well as the limited contrast between the valley-fill and bedrock. Thin, coarse-grained units and low contrast in the resistivity present challenges for constraining 1-D inversions. Thin units cannot be resolved and are merged, resulting in simplified models that reflect averaged apparent resistivity. Supplementary data (e.g., borehole resistivity logs) are useful for constraining complex multi-layer inversions, but where absent, complex models are not realistic. As the ratio of the resistivity of two layers decreases, there is more uncertainty in the placement of layer boundaries even though the root mean squared standard error of fit for the model may remain small (<6%). Nonetheless, when 1-D inversions are combined into resistivity-depth sections we interpret four generalized lithologies: 1) bedrock (∼10–30 ohm-m); 2) fine-grained sediment (clay, silt, fine sand, and diamict; 30–50 ohm-m); 3) medium-grained sediment (silt and sand; 40–80 ohm-m); and 4) coarse-grained sediment (sand and possibly gravel; 90 to >350 ohm-m). When the 2-D resistivity-depth sections are combined, there is 3-D continuity and the geometry of the Groundbirch Paleovalley can be traced. The valley is approximately 3–4 km wide with a maximum depth of about 120 m. The data suggest a local basal aquifer (medium- to coarse-grained unit) in the central survey area and possibly an unconfined aquifer towards the northwest region of the survey area. The EM-based model is consistent with models based on water well logs and field observations. Although the EM data remain exploratory, the resulting EM models provide clear guidance for groundwater resources management strategies.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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 teacher head, 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".