Mineralogy, geochronology, and stable isotope geochemistry of gold mineralization in the Belleisle Bay and Annidale groups, southwestern New Brunswick, Canada
Bibliographic record
Abstract
The New River and Annidale belts host several orogenic-related gold mineralized zones in southern New Brunswick, Canadian Appalachians. Gold mineralized samples were examined from the Devil Pike Brook deposit (New River Belt) and the Sheba Pit, North Fuchsite Zone, South Fuchsite Zone, East Scotch Settlement – BP, Grant Brook West, Henderson Settlement occurrences, and the Bald Hill deposit from the Annidale Belt. Almost all the gold mineralized zones are characterized by a typical alteration halo (chlorite, sericite, and fuchsite) directly related to auriferous quartz-carbonate veins hosted by greenstone belt volcano-sedimentary rocks and associated mafic dykes. The mineralization likely formed under greenschist facies conditions (300–450 °C), similar to other orogenic systems in the Canadian Appalachians. The ages obtained for the North Fuchsite Zone (U-Pb rutile age; 482 ± 16 Ma) and East Scotch Settlement – BP ( 40 Ar– 39 Ar age; 466.6 ± 4.3 Ma) occurrences indicate an Early to Middle Ordovician age for the mineralization. This time interval coincides with the Penobscot orogeny, followed by the emplacement of the Stewarton Gabbro (479 ± 2 Ma) shortly after the orogeny. This period is considered the primary event for gold mineralization in the Annidale area. The ages related to the auriferous Bald Hill Sb deposit ( 40 Ar– 39 Ar age; 422.8 ± 5.6 Ma), the Sheba Pit gold occurrence ( 40 Ar– 39 Ar age; 394 ± 17 Ma), and the Devil Pike Brook gold deposit (U-Pb rutile age; 348 ± 46 Ma) are younger than the North Fuchsite Zone and East Scotch Settlement – BP occurrences. These young ages are considered resetting ages due to several subsequent tectonic events (Salinic, Acadian, and Neoacadian orogenies) after the main mineralization event. However, based on structural relationships, the auriferous Bald Hill Sb deposit is interpreted as a younger system. The O isotopic results for quartz in the auriferous quartz veins from most gold occurrences in the Annidale Belt (δ 18 O +10.9 to +16.0 ‰) values fall within the typical range associated with metamorphic fluids. Sulphide minerals extracted from most gold occurrences within the Annidale Belt exhibit a δ 34 S range between 4.4 and 12.0 ‰, which aligns with the typical signature of fluids associated with orogenic gold deposits. In contrast, the δ 34 S results for the auriferous Bald Hill Sb deposit are close to 0.0 ‰, a characteristic indicative of sulphides originating from the mantle or through leaching of magmatic rocks. The Pb isotope values for this study indicate a heterogeneous lead source involving isotopic mixing between mantle, upper crust, and lower crust sources. These findings considered the Penobscot orogeny as a key gold-forming event in southern New Brunswick. They also suggest the presence of younger, possibly magmatic-hydrothermal systems such as Bald Hill. The results provide critical insights into fluid sources and the timing of mineralization.
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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 | 0.001 | 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) | 0.000 | 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".