Assessing primary versus secondary features in two pegmatite swarms with implications for the nature of pegmatitic systems
Bibliographic record
Abstract
Understanding the processes behind the formation and evolution of pegmatites, which host globally significant resources of strategic metals (e.g., Li, Ta, Nb, Sn, Cs, Rb, Y, REE) critical to the global renewable energy transition, is paramount for their exploration and exploitation. This study investigates the nature, origin and evolution of two distinct pegmatite swarms (i.e., the LCT-type Little Nahanni Pegmatite Group, NWT, Canada, and the NYF-type Highway 69 Pegmatite Group, Ontario, Canada) in order to address several unresolved aspects of pegmatite genesis, such as the origin of pegmatite-forming melts (i.e., anatexis versus fractional crystallization), nature of various pegmatitic textures (i.e., primary versus secondary), metasomatism and re-mobilization of rare-metal mineralization, and influence of the host rocks on pegmatites (i.e., open- versus closed systems). This study integrates various aspects of field observations that include detailed mapping, field and petrographic observations (transmitted light, BSE, SEM-CL), bulk whole-rock and trace-elements geochemistry (ICP-AES, ICP-MS), in situ mineral analysis (SEM-EDS), in situ trace-elements analysis (LA-ICP-MS), bulk and in situ stable isotopes (O, H) geochemistry (DI-IRMS, SIMS), and in situ U-Pb geochronology (LA-ICP-MS). The principal findings suggest that: (1) both anatexis and fractional crystallization of a parental melt are viable processes of pegmatite formation; (2) most macroscopic pegmatitic textures are primary and are generally preserved during sub-solidus evolution of pegmatites; (3) late-stage, fine-grained albitic and micaceous units associated with significant rare-metal mineralization are secondary; (4) secondary micro-features related to coupled dissolution-precipitation processes in pegmatites are profuse, despite being rarely reported, and are frequently associated with accessory rare-metal mineralization; and (5) pegmatites evolve as partially open systems during both magmatic and metasomatic stages with influence from the host rocks, and in some cases, external fluids.
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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 | 0.000 |
| 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".