U-Pb geochronology of the South Mountain Batholith, Nova Scotia
Bibliographic record
Abstract
The South Mountain Batholith (SMB) is a composite peraluminous intrusion in southwestern Nova Scotia and the largest granitoid body in the Appalachian Orogen. The batholith comprises early stage biotite-granodiorite to biotite-monzogranite and a later stage of leucomonzogranite to leucogranite plutons that are associated with numerous sub-economic to economic polymetallic (Sn, W, Mo, Cu, Ta, Nb, Zn) deposits, including East Kemptville, a past-producing Sn-Zn-Cu-Ag(-In) deposit. The timing and duration of emplacement for intrusive phases that make up the SMB remain poorly constrained. The U-Pb zircon age results from Sensitive High-Resolution Ion Microprobe (SHRIMP) analyses in this study constrain the emplacement age of the early and later phases across the SMB, as well as provide insight into mineral potential in the intrusive complex. Zircons from five plutons in the batholith were analyzed; including one early phase granodiorite, to compliment previous U-Pb zircon dates from similar phases (ca. 381-373 Ma), and four late phase leucogranitic plutons. Results indicate the early granodiorite to be 380.9 ± 3.0 Ma and the later leucogranites to range between 376.0 ± 3.0 Ma and 372.8 ± 3.0 Ma. The ca. 15 Ma from oldest to youngest crystallization ages mark the beginning and end of SMB construction. Due to overlapping errors, more precise dating is necessary to determine whether the late stage polymetallic-mineralized plutons intruded as a discrete magmatic event to the early stage plutons, or as part of a protracted Late Devonian magmatism in the region.
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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 | 0.000 |
| 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 | 0.001 |
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".