A Fluid Chemical Study of the World-Class, Intrusion-Related Archean Windfall Gold Deposit, Quebec, Canada
Bibliographic record
Abstract
Abstract Windfall is a world-class Archean intrusion-related Au deposit (7.4+ Moz of Au) located in the underexplored Urban-Barry greenstone belt (Quebec, Canada). The deposit remains an enigmatic Au setting—its intrusion-related features contrast with the more common orogenic deposit type in the Au-endowed Abitibi greenstone belt. Mineralization consists of quartz-pyrite-carbonate ± tourmaline veins and stockworks that cut sericite-pyrite ± silica ± tourmaline ± fuchsite replacement zones, all of which overprint a swarm of 2697.6 ± 2.6 Ma quartz-feldspar porphyry dikes. That the ore zones and quartz-feldspar porphyry dikes are cut by a later set of 2697.6 ± 0.4 Ma quartz-feldspar porphyry dikes constrains mineralization temporally and spatially to intrusive activity. To further address the deposit genesis, ore petrology integrated with scanning electron microscopy-energy dispersive spectrometry analysis and cathodoluminescence imaging, laser ablation-inductively coupled plasma-mass spectrometry mapping of pyrite, fluid inclusion studies, and in situ secondary ion mass spectrometry isotopic studies (O, S) were completed. Ore-related sulfides are dominated by pyrite with lesser arsenopyrite, sphalerite, chalcopyrite, tennantite-tetrahedrite, galena, gold, electrum, and minor Sb-rich and telluride alloys. Four pyrite generations (Py1-Py4) occur, with elemental maps indicating primary Au is related to As-rich Py2 that is also enriched in Ag-Sb-Hg-Cu-Zn-Pb-Bi-Te. The δ34Spyrite values are similar for Py1 to Py3, with an inferred δ34Sfluid of ~5‰ consistent with a magmatic reservoir, whereas δ18Oquartz for both igneous (avg = 8.4‰, n = 28) and vein (5.7–14.6‰, n = 53) material suggests mixing of a magmatic fluid with an 18O-poor reservoir. Fluid inclusion studies from pre- to postmineralization veins indicate the predominance of a carbonic (±CH4) fluid, with rare aqueous-carbonic (CO2 = 5–98 mol %) and variably saline aqueous types. Whereas the data are considered to best reflect an intrusion-related deposit model, we note that some data, such as the carbonic-rich nature of fluid inclusions and large range in δ18Oquartz, are equivocal in regard to their meaning, and thus further studies are needed to resolve some aspects of this ore system.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.008 | 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 teacher head, 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".