Tracking the porphyry-epithermal mineralization transition using U-Pb carbonate dating
Bibliographic record
Abstract
Abstract Key metals important for the green energy transition concentrate during magmatic-hydrothermal processes. In porphyry deposits, epithermal mineralization can overprint earlier higher-temperature systems. It is not well understood whether mineralization occurs in a single evolving system or forms during pulsed, episodic overprinting events. The timing and duration of fluid flow therefore remain key data gaps in deposit models, but they are essential factors for understanding metal (re)mobilization and concentration processes. Carbonates are common gangue minerals that precipitate during fluid flow and can be dated using the U-Pb method, thereby directly dating hydrothermal processes. Here, 41 new U-Pb dates from a fault-controlled porphyry-epithermal system in Yukon, Canada, reveal a >50 m.y. record of carbonate precipitation between ca. 77 and 19 Ma. Results support a model of pulsed, episodic fluid flow, rather than a single evolving system, where epithermal carbonate precipitation at ca. 74–67 Ma was both coeval with and significantly postdated Cretaceous porphyry-related magmatism. Overprinting events at ca. 62–56 Ma, ca. 51–47 Ma, and younger than 40 Ma were not responsible for primary metal deposition but may have contributed to metal enrichment. Carbonate dates coincide with periods of brecciation and fault slip. Fault movement therefore enabled episodic overprinting by epithermal mineralization, mobilizing and (re)concentrating metals. This comprehensive reconstruction of a long-lived magmatic-hydrothermal system tracks the transition from porphyry to epithermal environments, demonstrating the power of carbonate U-Pb dating for critical minerals research.
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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 | 0.000 | 0.000 |
| 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 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".