Longevity of fault-controlled fluid flow within a Cu-Au-Mo porphyry (Yukon, Canada) revealed by coupled U-Pb carbonate geochronology and clumped isotope analysis
Bibliographic record
Abstract
Carbonate veins are ubiquitous in many ore deposits and are often interpreted as a late stage or cross cutting fluid flow events in the ore deposit history. Faults accommodate rock displacement and the resulting zones of weakness act as conduits for magma and localised magmatic-hydrothermal fluid flow, leading to the formation of ore deposits. Dating of both low temperature veins and brittle fault material has been notoriously difficult because of a lack of ‘datable’ material. Using innovative techniques, it is now possible to date carbonate with the U-Pb isotopic system.Here we use in-situ U-Pb carbonate geochronology to date a variety of fault material and mineralised and unmineralised veins within a major fault-controlled Cu-Au-Mo porphyry system in the central Yukon, Canadian Cordillera. Over 50 samples have been dated, revealing a long history of faulting and fluid flow in the deposit spreading over 10s of millions of years between ~75 Ma and <20 Ma. We combine petrography, U-Pb carbonate geochronology, trace element geochemistry, and clumped isotope analysis to interpret the full temperature-time evolution of the fluids within the deposit. Our results show the carbonate veins crystallised during the main ore-forming event at ~75 Ma. Subsequently, there was a prolonged period of fault-controlled fluid pulsing that likely concentrated metallic minerals in the deposit. The findings show that carbonate veins are not always late features within ore deposits and are an underutilised resource for understanding the full temporal and fluid evolution of a system. Carbonate U-Pb geochronology is therefore potentially incredibly useful for telling the previously untold and long history of fluid flow in a variety of deposit types.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| 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".