Hydrothermal evolution of volcanogenic Zn-Cu-Pb deposits, Taylors Brook showing, Stirling Belt, southeastern Cape Breton Island, Nova Scotia
Bibliographic record
Abstract
The Taylors Brook showing is a suspected volcanogenic massive sulfide (VMS) occurrence (Zn-Pb-Cu-Au-Ag) that occurs within the ~680 Ma Stirling volcanosedimentary-plutonic belt, southeastern Cape Breton Island, Nova Scotia, Canada. In addition to mineralized mudstones, there are 7 associated hydrothermal vein types, characterized using three criteria: vein-filling mineral composition and alteration style, cross cutting relationships and mineralization. Mineralized (Zn-Cu-Pb-Sc-Y-Ag-Te) veins show propylitic and potassic alteration assemblages. Compositional zoning in epidote and a pyrrhotite-smythite replacement reaction indicate that the hydrothermal fluid was experiencing fluctuations in /O2 and cooling, respectively, rendering the metals less soluble causing their precipitation. \nBulk rock geochemistry indicates mineralization anomalies are associated with host rock Zn-Pb anomalies in pyritic mudstone units and Cu anomalies in type IA (epidote-actinolite-calcite-K-feldspar-quartz-pyrite) veins. Fluid inclusion data from two generations of calcite in later type V veins suggest a CaCl2-rich hydrothermal brine responsible for metal transport and deposition with bulk salinities ranging between 43-54 wt% total salt (absolute: 33-50 wt% CaCl2 and up to 20 wt % NaCl). The homogenization temperatures for calcite A-hosted inclusions range from 106-306[degree]C (n=21) and in calcite B-hosted inclusions from 212-331[degree]C (n=91). Isochore ranges were plotted using microthermometric data, paired with a po-py equilibrium boundary constraint limits trapping conditions to a maximum of 400[degree]C and 5kbar. \nThe distinct Ca-Cl-rich brine composition can only be formed naturally under specific conditions. There are four conceivable explanations for this Ca rich fluid: boiling, cation exchange between Na and Ca, evaporation of Ca-rich paleoseawater and dissolution of Ca-evaporites. However, the combination of high salinity and high Ca is only possible via the latter two processes. The Taylors Brook showing has comparable mineralization to the Stirling deposit, and the Duck Pond-Lemarchant deposits of Newfoundland but has an inconsistent fluid chemistry with VMS deposits.
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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 | 0.001 |
| 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) | 0.001 | 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".