Imaging the upper part of the Red Lake greenstone belt, northwestern Ontario, with 3-D traveltime tomography
Bibliographic record
Abstract
Seismic reflection line 2B was shot across the Archean Red Lake greenstone belt and Sydney Lake fault zone that marks the northern boundary of the English River metasedimentary belt, as part of the Western Superior Lithoprobe transect. Three-dimensional tomographic inversion of first arrival traveltimes recorded in this survey delineate the subsurface to depths as great as 1.5 km around this crooked two-dimensional seismic line. Within the Red Lake greenstone belt, P-wave velocities of 6.2–7.0 km s–1 occur at 500 m depth in the Mesoarchean Balmer assemblage, clearly distinguishable from the lower velocities of 5.1–6.1 km s–1 of the Neoarchean Confederation assemblage. Although the overall range of velocities in the metasedimentary rocks of the English River subprovince is similar to that found in the Confederation assemblage, lower velocities of 5.1–5.4 km s–1 are found in the upper 300 m of the metasedimentary rocks. In particular, two 2–3 km wide, east-northeast-striking zones of low velocity are associated with the Sydney Lake fault zone and the Pakwash Lake fault zone. Correlation of the velocities with the coincident reflection section suggests that these two faults delineate a fault-bounded block in the hanging wall of a more northerly fault zone that crops out within the Uchi subprovince. Anomalous regions of low velocity, which occur at the boundary between the Confederation and Balmer assemblages, and within the Balmer assemblage, may also be related to shear zones that have minimal near-surface expression, felsic lithologies, or hydrothermal alteration of the basalts.
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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 | 0.001 | 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) | 0.002 | 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".