Shock brecciation around the Kidd Creek deposit, Abitibi belt, Canada
Bibliographic record
Abstract
The Kidd–Munro assemblage, Abitibi belt, Canada, is an ultramafic–mafic–felsic volcanic sequence that contains the giant Kidd Creek volcanic-hosted massive sulfide (VMS) deposit. The Kidd basin, 1.6 km northeast of the deposit, contains pervasively brecciated pillowed and massive basalts. The breccia is distinctly different from most breccias in volcanic rocks, which form through volcanic processes or during later deformation or alteration. The Kidd Creek breccia occurs pervasively through otherwise undeformed pillow interiors and margins, and also in localized corridors of particularly intense brecciation. Clasts are angular, up to 4 cm wide, hosted in a very fine-grained matrix, and commonly show jig-saw fit texture. The chemical compositions of the breccia fragments and matrix are generally similar, although the matrix is slightly enriched in high field-strength elements (HFSE) and heavy rare-earth elements (HREE) and depleted in some mobile elements, such as Rb and Ba. The breccia contains altered basaltic clasts and fragments of in-filled amygdales and is crosscut by late-stage quartz–carbonate–sulfide veins. The observations imply that the breccia was formed in-situ, with minimal transport of material, and developed after solidification of the volcanic rocks. In-situ breccias, such as these, are known to form proximal to major fault zones, but no such structure occurs in the vicinity of the Kidd Basin. We suggest the brecciation was caused by the propagation of shock waves from explosive volcanic eruption, perhaps related to the emplacement of felsic volcanic rocks observed in the Kidd Creek Mine. The breccia was subject to enhanced hydrothermal fluid flow, perhaps linked to the formation of the ore deposit.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".