Characterization and Timing of Mineralization in the Garrison Gold District, Southern Abitibi Greenstone Belt, Canada
Bibliographic record
Abstract
Abstract The decrease in gold discoveries is affecting the deployment of new technology and the general society demand, demonstrating the need for new gold exploration approaches. To date, gold exploration remains primarily focused in areas near well-known large gold districts. We demonstrate the potential for new discoveries and significant resource expansion in the Abitibi greenstone belt distal from the giant gold districts across the belt. Unlocking of additional resources in the Garrison district was accomplished by identification of zones of compentency contrast, which resulted in a variety of locally complex and unrecognized structural traps receptive to gold. Our approach is applicable to other little-explored areas in the Abitibi greenstone belt and other orogenic belts worldwide. The Garrison district, situated in the southern part of the Abitibi greenstone belt in the Superior province, lies along an ~3-km NE-trending segment of the gold-rich, Archean Porcupine-Destor deformation zone. The district contains several discoveries, which include the Buffonta deposit hosted in mafic volcanic rocks, the syenite-hosted 903 deposit, and the albitite dike-hosted Jonpol deposit. These deposits occur along high-strain zones developed in embayments and elongate, NE-trending domains of talc-chlorite-serpentine–altered ultramafic rocks, which localized strands and splays of the Porcupine-Destor deformation zone. In addition, the Garrcon deposit comprises northerly-trending gold-bearing quartz veins and lamprophyre dike swarms hosted in sedimentary host rocks that are bounded by high-strain zones. The intrusive rocks in all of these deposits were emplaced prior to gold deposition. They provided a competent substrate in areas of heterogeneous strain that localized gold mineralization. Initial alteration made the surrounding volcanic and sedimentary rocks also rheologically competent. This resulted in enhanced hydrofracturing and the formation of paragenetically late gold-bearing quartz veins. Widespread albite-pyrite-carbonate alteration in all of the gold deposits temporally overlapped with gold mineralization. New U-Pb zircon geochronology data reveal that ~2719 to 2712 Ma volcanism was followed by granitic magmatism and emplacement of a series of ~2683 to 2672 Ma dikes. One Re-Os analysis of a synmineralization molybdenite sample indicates that orogenic gold was deposited at 2671 ± 12 Ma. This is comparable to published ages of major orogenic gold deposits throughout the southern part of the Abitibi greenstone belt, indicating a broadly synchronous principal gold event across the belt.
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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 | 0.004 | 0.004 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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".