Granite-hosted mineral deposits of the New Ross area, South Mountain Batholith, Nova Scotia, Canada.
Bibliographic record
Abstract
The most evolved rocks of the South Mountain Batholith host polymetallic (Sn-W-U-Mo-Cu-Mn) mineral deposits in the New Ross area (NRA). This project presents new data (fluid inclusions, stable isotopes, mineral chemistry, and 40Ar/39Ar and 187Re/187Os dating) to define the hydrothermal fluids related to the mineralisation of the NRA, and to create an integrated model for the origin of the mineral deposits. Single-grain Ar/Ar laserprobe ages for white micas from unmineralised and mineralised samples range from 382 to 320 Ma. Molybdenite Re/Os ages on two pegmatite samples are 377 +/- 3 Ma and 371 +/- 3 Ma. The main phases of hydrothermal activity leading to polymetallic mineralisation occurred in close temporal relationship to granite crystallisation at ∼380 Ma, and episodic reheating events occurred at ∼371 Ma and ∼320 Ma, partially resetting the Ar/Ar system. Three distinct fluids in the mineral deposits of the NRA are: (i) a Na/K-rich magmatic fluid; (ii) a Ca-rich metamorphic fluid; and (iii) a meteoric fluid. Mixing of these fluids occurred, implying that the three fluids were contemporaneous. The isotopic compositions (delta 18O, deltaD) of white mica from unmineralised and mineralised samples of the NRA, and deltaD values for fluid inclusion extracts from coexisting quartz, record a transition from a magma-dominated, low water/rock ratio system to a fluid-dominated, higher water/rock ratio system, into which meteoric water infiltrated at the time of SMB crystallisation and greisen/vein formation. Fluctuating pH conditions of hydrothermal fluids at the contact with host granitoid rocks and variations in redox conditions, triggered by incursion of increasing amounts of meteoric fluid along deep-penetrating faults as the system evolved from magmatic to hydrothermal, caused metal deposition. Over ∼10 My, the concurrence of highly evolved granitic melts rich in incompatible elements in the late-stage of granite emplacement with intense fluid circulation, particularly those of meteoric origin, formed the NRA mineral 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 | 0.000 |
| 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) | 0.004 | 0.001 |
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".