Geology, U–Pb zircon geochronology, and geochemistry of PGE-bearing Neoarchean and Paleoproterozoic gabbroic rocks of the Peter Lake domain, southern Hearne craton, Canada
Bibliographic record
Abstract
The Peter Lake domain, a component of the Hearne craton in Saskatchewan, includes several intrusive complexes ranging in age from 2.70 to 1.83 Ga. Two gabbroic complexes (Swan River and Porter Bay) together represent one of the largest accumulations of Precambrian mafic intrusion, both metamorphosed at amphibolite facies. Sulfide-poor PGE occurrences are found in both complexes and share many textural and lithological characteristics with magmatic contact-type PGE–(Ni–Cu) deposits such as the chaotic Lac des Iles pluton and with layered stratiform deposits of large layered intrusions such as Bushveld or Stillwater. Lithologically, both complexes are dominated by leucocratic gabbronorite and gabbro, locally characterized by cumulate layering, cross-bedding, brecciated, and pegmatitic textures. U–Pb zircon crystallization ages between 2562 and 2560 Ma were obtained for the Swan River complex. sulfide formation is interpreted to be of magmatic origin rather than remobilized, as had been speculated by exploration geologists, and is therefore of the same age as the host gabbro. Geochemical data support the interpretation of a mantle plume origin in a subduction environment for the Swan River complex. The Porter Bay complex is much more restricted in areal extent and a leucocratic gabbronorite yielded a U–Pb zircon age of 1913 ± 1 Ma, which is interpreted as the crystallization age and the time of sulfide formation. Major and trace element geochemical data of Porter Bay complex rocks show a considerably more evolved character than the Swan River complex, and is interpreted as indicating emplacement in a continental arc environment.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".