Abstract: The Baring Granite and St. Stephen Gabbro of New Brunswick and Maine: petrology, geochemistry, and tectonic setting
Bibliographic record
Abstract
The Baring Granite and St. Stephen Gabbro are a probable comagmatic suite situated in the area of St. Stephen, New Brunswick and Calais, Maine. The intrusions are traditionally included as part of the Moosehorn Igneous Complex, in addition to the Staples Mountain Gabbro, the Calais Gabbro-Diorite and several small unnamed diorite intrusions, within the Coastal Maine Magmatic Province. They intruded the Cookson Group of the St. Croix terrane of the northern Appalachian orogen, a sequence of quartzofeldspathic sedimentary rocks, quartzite, carbonaceous pelite, and minor mafic tuff. The age of the intrusions is not well constrained but previous U-Pb geochronology suggested a Silurian age. A suite of samples has been collected from the intrusions for more detailed investigation of the petrology, petrogenesis, tectonic setting, and age. The St. Stephen Gabbro · consists of complexly intermingled olivine gabbro, olivine gabbronorite, and olivine norite, with less abundant gabbro, gabbronorite, norite, troctolite, anorthosite, and dunite. Previous chemical studies are inconclusive with respect to chemical affinity and tectonic setting at the time of emplacement. The pluton hosts numerous discrete sulphide mineralization zones. Mineralization has been interpreted to have formed in two stages, including orthomagmatic (Ni-Cu-Co) mineralization and a later hydrothermal mineralization (Ni-Cu-Zn). The Baring Granite is coarse-grained, hypidiomorphic, granular, and is composed of microcline, plagioclase, quartz, hornblende, and biotite. Accessory minerals include zircon, apatite, and titanite. The mafic mineral content of the Baring Granite is quite low, generally 10% or less. Locally, the Baring Granite and St. Stephen Gabbro are intensely intermingled, with inconclusive cross-cutting features, such as enclaves and dikes visible at the outcrop scale. Cuspate intermingling textures suggest that the granitic magma intruded the gabbroic rocks prior to complete crystallization. Diorite is typically present between the gabbroic and granitic rocks. The cross-cutting relationships, where a gabbro outcrop is cut by diorite and then by granite may suggest that intense intermingling occurred at the onset of granite intrusion, but became less intense as emplacement of the Baring Granite continued. Comparison of the Baring Granite and St. Stephen Gabbro to other Silurian-Devonian plutons of the Coastal Maine Magmatic Province and equivalent (?) units in New Brunswick such as the Bocabec Complex may help in the definition of terrane boundaries in southwestern New Brunswick and southeastern Maine.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 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".