Near-Surface Volcanic Rocks in the SE Nechako Basin, BC: Results of Interpretation of Seismic Reflection Data using First-Arrival Tomographic Inversion
Bibliographic record
Abstract
Summary Near-surface estimates of P-wave velocity are derived from the tomographic inversion of seismic firstarrivals, to investigate the character of rocks in the south-eastern Nechako Basin. Near-surface seismic imaging is poor due in part to an extensive cover of Eocene and Neogene volcanic rocks, Quaternary drift, and vegetation. The depth of maximum ray density (~272-277 m) derived from the tomographic models constrains the thickness and extent of Eocene Endako Group volcanic rocks near well b-82-C, where rays converge on underlying high-velocity (3900 ms -1 ) sandstone refractor. As Eocene volcanic rocks have a typically higher mean (depth interval, 0-175 m) velocity (~2400-3200 ms 1 ) than Chilcotin Group volcanic rocks and Quaternary drift (~1500-2500 ms -1 ), interval velocity may be used to constrain the distribution of the Eocene rocks. Chilcotin Group rocks of the breccia rich Bull Creek facies, exhibit low interval velocities (~1500-1700 ms -1 ) and a greater depth of maximum ray density in the Chilcotin River area. These results are consistent with the interpretation of an increased thickness of the Chilcotin Group in paleochannels. Regionally the Chilcotin Group has a limited affect on interval velocity, suggesting that it is thin and/or of a lithology which has a similar velocity to the underlying rocks. The presence of low interval velocity is more commonly indicative of thicker drift.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".