Granite-hosted mineral deposits of the New Ross area, South Mountain Batholith, Nova Scotia, Canada: P, T and X constraints of fluids using fluid inclusion thermometry and decrepitate analysis
Bibliographic record
Abstract
The 370 Ma peraluminous South Mountain Batholith (SMB) intrudes Meguma Supergroup metasedimentary rocks in Nova Scotia. The New Ross area of the SMB contains polymetallic mineralisation (Sn, W, U, Mo, Cu and Mn) in pegmatite, greisen and vein directly or indirectly associated with highly evolved fractions of the SMB. Eight mineral deposits from this area have several fluid inclusion types hosted by quartz: (1) monophase liquid (L); (2) monophase vapour (V); (3) aqueous, L-V (4) aqueous, L-rich + solids; (5) aqueous, L-rich + halite. Inclusions have irregular to equant shapes and are pseudo-secondary or secondary. The irregularity and variability of L:V ratios within fluid inclusion populations suggest post-entrapment modifications of inclusions (i.e. necking). Thermometric data indicate three distinct fluids in terms of salinity: (1) 19-25 wt. % equiv. NaCl (rarely 14-25 wt. % NaCl equiv.), (2) 29-43 wt. % equiv. NaCl, and (3) 0-9 wt. % equiv. NaCl. Temperatures of first melting and ice/hydrohalife melting indicate CaCl2 in solution. Proximity of the deposits to Meguma Supergroup metasedimentary rocks suggests that this Ca component may be externally derived. The majority of the low-salinity fluid population has the composition of meteoric water. Electron microprobe analyses of artificially decrepitated mounds identify Na, Ca and K as major solutes, with a continuum in terms of compositions. Other solute components in the mounds are Fe and Ba, and a variety of metals of unknown speciation also occur (Cu, Zn, Fe, Ni). Homogenisation temperatures (Th) range from c. 80°C to 370°C, but for inclusion assemblages the range is 10°C to 20°C. Given the 3 kbar depth of emplacement of the SMB, estimated entrapment temperatures are c. 200°C to 550°C. The fluid inclusion data appear to reflect: (1) trapping of mixed Na-K-Ca brines during isobaric cooling in pegmatite and greisen deposits as indicated by large ranges in Th; (2) formation of deposits at different ambient pressures (i.e. depth); and (3) mixing of fluids of different reservoirs (i.e. magmatic, metamorphic, meteoric).
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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 | 0.002 | 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".