Shallow crustal structure in the Meadowbank River - Tehek Lake area: insights from gravity and magnetic modelling
Bibliographic record
Abstract
Relatively closely-spaced gravity data measured along two traverses near the Meadowbank gold deposits near Tehek Lake have been modelled in concert with regional magnetic data to provide a preliminary pictu.re of upper crustal structure and rock types. Modelling has also been completed along two regional gravity profiles, indicating that Archean supracrustal rocks attain thicknesses ranging from 2.8 km to 8.3 km in fairly localised keels, but are generally 1000 rn to 2000 n1 thick over large sections of crust. Parts of thinner sections of supracrustal rocks are modelled to be overlain by very thin (<400 m thick) sheets of Archean granitic rocks that may be in intrusive or tectonic contact. Regional modelling also suggests the presence of thin (~3 km thick), buried sheet-like Proterozoic granitic bodies. Modelling along the detailed gravity traverses yields similar thicknesses of supracrustal rocks, generally between 500 m and 1700 m thick, which are also overlain by thin sheets of Archean granitic rocks. Modelled contacts between supracrustal units are typically very steep. A notable product of magnetic modelling is a large volume of high 1nagnetic susceptibility iron formation distributed in many narrow, steep units extending from the surface or near-surface to depths ranging from about 1000 m to 1200 m. These depths probably represent minimum depths because of limitations in modelling steep, narrow bodies. Another revelation of modelling is the large volumes of komatiite predicted as extensions of relatively small units of komatiite mapped at surface. Granitic bodies of possible Proterozoic age have been modelled in the upper crust. One extends vertically over about 4800 1n, whereas others ex tend no deeper than 1400 m below surface.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".