Borehole magnetic surveys in weakly magnetic sediments (Chicxulub impact crater) versus strongly magnetic volcanics (Bathurst mining camp)
Bibliographic record
Abstract
Borehole navigation surveys performed using a triaxial fluxgate magnetometer record the change in orientation of the magnetic vector versus depth. Variations in the orientation of the magnetic vector arise from either on- or off-hole magnetic sources. On-hole magnetic sources associated with magnetic property fluctuations in the immediate wall of the borehole (i.e., susceptibility) and (or) remanence polarity changes produce sharp-edged anomalies. Off-hole magnetic sources, caused by a magnetic body near, but not penetrated by, the borehole, produce broad smooth anomalies. Prior to the interpretation of borehole magnetic anomaly logs, data corrections must be applied. Data from each of the magnetic and tiltmeter sensors must be corrected for differential gain, base value offset, and nonorthogonality. By using a probe with two sets of triaxial fluxgates, it is possible to detect along hole magnetic field rotations, which compromise the borehole navigation calculations. After rotation into geographic coordinate space, borehole vector magnetic data from the Chicxulub impact crater in Mexico showed no evidence for any systematic change of magnetic property versus depth. What was originally interpreted as reversal stratigraphy has proved to be minor changes in borehole geometry. Borehole magnetic data from a borehole through the Stratmat deposit, located in the Bathurst mining camp, New Brunswick, show strong off-hole and on-hole anomalies associated with the pyrrhotite-rich ore bodies.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".