Hydrothermal fluid chemistry and flow paths associated with the Archean Matagami VMS system, Abitibi subprovince, Canada
Bibliographic record
Abstract
Cathodoluminescence reveals that volcanogenic massive sulfide (VMS)-related quartz from the sim;2.7 Ga Abitibi greenstone belt, Canada, is of preserved hydrothermal origin. Fluid inclusions hosted within the quartz preserve samples of Archean VMS-related hydrothermal fluid. Microthermometry on ore-hosted primary liquid-vapor inclusions from the Matagami deposits indicates that the VMS hydrothermal fluid was highly saline (16.2 +/- 4.7 eq.wt.% NaCl-CaCl 2 [1sigma; n = 230]) and of moderate temperature (Tt = 208 +/- 32°C [1sigma; n = 230]). Quartz-epidote veins located in the hydrothermal cracking horizon (HCH) of the Bell River Complex (BRC) at Matagami host primary liquid-vapor-halite inclusions. These inclusions are samples of the deep-seated equivalent to the VMS ore-hosted hydrothermal fluid and were trapped as high-temperature brines (Tt = 373 +/- 44°C [1sigma; n = 92]; 38.2 +/- 1.9 eq.wt.% NaCl [1sigma; n = 92]) interpreted as phase separated products of (modified) seawater, an exsolved magmatic fluid, or a combination thereof deep within the hydrothermal system at sim;650°C and a near-lithostatic pressure of 90 MPa. X-ray diffraction (XRD) has identified large VMS-related hydrothermal alteration signatures, which extend well beyond ( sim;1,000+ m) the limits of the Matagami deposits. These signatures include hanging wall alteration assemblages probably produced during the waning stages of VMS hydrothermal activity, which are characterized by relatively low temperature fluids (Th = 76° to 177°C [n = 212]) of variable salinity (6.0 eq.wt.% to 32.4 eq.wt.% NaCl-CaCl2 [n = 212]) and high apparent CaCl2 content (XNaCl
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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".