Petrogenesis of Massive Sulfide Ores and Associated Globular Sulfide Texture in Raglan Horizon: Implications for Exploration of Concealed Orebodies at Depth
Bibliographic record
Abstract
The komatiitic Raglan Horizon in northern Quebec hosts one of the largest komatiiteassociated magmatic sulfide deposit groups in the world.Although the origin and chemical composition of the parental magma are relatively well studied, the physical processes responsible for formation of individual orebodies and closely associated globular sulfide texture are still poorly understood.In this study, we investigate the chemical compositions and physical nature of the sulfide accumulations to shed light on the ore-forming processes in komatiite-related systems.Thermodynamic modeling shows that the majority of the compositional variability of the sulfide-bearing rocks can be attributed to the difference in the mass ratio between silicate and sulfide melts (R-factor).The regional variations in the compositions of individual orebodies suggest that they occurred in highly localized environments that record only local magmatic conditions, and that the sulfide mineralization did not reach equilibrium with a single regionally continuous silicate magma system.Each zone preserves a unique signature of assimilation, sulfide segregation, and sulfide crystallization; hence they likely represent separate magmatic pulses within the larger Raglan system.The anomalously high Pd/Pt ratios in sulfides from Raglan, as well as many other major magmatic sulfide deposits, can be attributed to assimilation of C-rich sediments followed by saturation and removal of Pt-rich alloy in sulfide-undersaturated silicate iii magma.This finding emphasizes the significance of the introduction of carbon-rich sediments and/or volatiles to the parental magma in forming major magmatic sulfide deposits.The chemical analyses of the compositions of sulfide globules and massive sulfide accumulations in Raglan illustrate that sulfide globules, regardless of their spatial locations, share the same geochemical signatures with the underlying massive sulfide ores.Furthermore, systematic analyses of the size distributions of sulfide globules suggest that the globules reflect a mixed population of large, transported globules deposited in the early stage and finer sulfide droplets deposited in a later stage.An oreforming mechanism is proposed which indicates a genetic relationship between the occurrence of dense populations of sulfide microdroplets and massive sulfide ores.In addition, a strong spatial relationship between samples with high globule number density and massive sulfide accumulations is found which demonstrates the potential of using globule or bleb number density as a pointer to massive sulfide orebodies.First and foremost, I would like to express my sincere gratitude to my thesis supervisor, Dr. Jim Mungall of the department of Earth Science at
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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) | 0.002 | 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".