INVESTIGATION INTO POTENTIAL MAGMATIC CONTRIBUTIONS TO VOLCANOGENIC MASSIVE SULFIDE DEPOSITS: METHOD DEVELOPMENT FOR LA-ICP-MS ANALYSIS OF FLUID INCLUSIONS AND CRITICAL ASSESMENT OF THE WINDY CRAGGY DEPOSIT, NORTHWESTERN BRITISH COLUMBIA, CANADA
Bibliographic record
Abstract
In recent years, the existence of variable magmatic contributions to the mineralizing fluids in the formation of volcanogenic massive sulfide (VMS) deposits has been gaining acceptance in the scientific community. The world-class Windy Craggy Cu-Co-Au deposit (>300 MT @ 2.12 wt.% Cu) located in northwestern British Columbia is the ideal location to investigate this potential for multiple reasons: 1) a previously completed study documented fluid inclusions with anomalously high salinities relative to other VMS deposits; 2) Windy Craggy has an atypically large size and Cu grade compared to other VMS deposits. In this study a method was developed using an excimer (193 nm) laser ablation system interfaced to a quadrupole inductively coupled plasma mass spectrometer, which proved effective in quantifying key metals and metalloids in the inclusion fluids considered by many to be indicative of magmatic contributions to hydrothermal ore deposits. Despite the highly transient nature of the signal from the low salinity (most 6 – 16 wt.% eq. NaCl) inclusions, , of the total 34 elements that were monitored, Na, Mg, K, Ca, Mn, Fe, Co, Cu, Zn, Sr, Sn, Ba, Ce, Pb and Bi were consistently detected and quantified. Furthermore, Cl, Sb, Cd, Mo, Rb, Br, and As were also detected in a significant number of inclusions. Positive correlations between Cu, Mn, Zn, Sb, Sn and Bi were observed. The Ca/Na values in the fluid inclusions are greater than seawater and generally similar to values reported from other maficdominated VMS systems. The host lithologies and mineralization (footwall argillite, relatively fresh to highly altered footwall mafic volcanic rocks and stringer and massive sulfide) from Windy Craggy were also bulk geochemically analysed. The fluid inclusions show similar trends and overlap the host rocks in Fe vs Mn and Cu vs Zn, but show clear excesses over the host rocks, and in particular the sulfide-rich samples, in Sb, Sn and Bi that are commonly ascribed as indicative of magmatic contributions in other deposit types. These excess values strongly indicate a direct magmatic contribution to the Windy Craggy ore-forming fluids, as opposed to simply reflecting leaching of metals from the footwall sedimentary and igneous rocks.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".