Devonian intrusions of southwestern New Brunswick, Canada: U-Pb geochronology, petrogenesis and genetic constraints on gold mineralization
Bibliographic record
Abstract
The Clarence Stream intrusion-related gold deposit is hosted within metasedimentary and metavolcanic sequences of the Ordovician Cookson and Silurian Mascarene groups that were intruded by several phases of the Late Silurian to Early Devonian Saint George Plutonic Suite. Based on geochemical and geochronological data, the intrusive rocks in the deposit are categorized into three distinct suites, including gabbroic, granitoid, and Whittier Ridge Granite (WRG). The gabbroic suite is the same as the East Branch Brook metagabbro intrusion, which exhibits a subalkaline mafic composition fractionated from a depleted mantle in a suprasubduction zone setting. The granitoid suite shows the same geochemical characteristics and age as the metaluminous to slightly peraluminous Magaguadavic Granite and its fractionated phases. The WRG suite reflects characteristics of calc-alkaline, metaluminous to peraluminous I-type granites in the area, such as Sorrel Ridge and Mount Douglas granitic plutons. In situ U-Pb zircon geochronology yielded an age of 419.5 ± 3.8 Ma for a monzodiorite from the gabbroic suite. Porphyritic granite and alkali granite from granitoid suite yielded U-Pb zircon age of 402.4 ± 1.8 Ma and 394.3 ± 3.8 Ma, respectively. Geochronologic data from the WRG suite reflect two different crystallization ages of 383.8 Ma (382.4 ± 3.1 to 385.1 ± 4) and 372.4 Ma (367.4 ± 1.3 to 377.1 ± 1.9). Several pieces of evidence demonstrate that the gold mineralizing events occurred after the emplacement of the East Branch Brook metagabbroic dykes and are linked to the various intrusive phases of the nearby syntectonic Early Devonian Magaguadavic Granite. The absence of gold and sulphide mineralization in felsic dykes related to the WRG confirms that this plutonic body formed adjacent to the gold zones after the main gold mineralizing event.
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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 | 0.004 |
| Science and technology studies | 0.002 | 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) | 0.002 | 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".