Petrographic analysis and determination of protoliths and pressure-temperature conditions for the Pocologan metamorphic suite, southern New Brunswick
Bibliographic record
Abstract
The Pocologan metamorphic suite is a belt of metamorphosed and deformed sedimentary, volcanic and deformed granitoid rocks in southern New Brunswick, west of the city of Saint John. It occurs in faulted contact with the Kingston terrane to the north and the Brookville terrane to the south. Previously, this belt of rocks was included mainly in the Pocologan Mylonite Zone but many of the rocks in the suite are not mylonite. Mapping and petrographic study of 73 samples showed that the Pocologan metamorphic suite consists of five map units. Northwestern and southeastern belts of mylonite are separated by belts of (from northwest to southeast) metatuffaceous rocks, amphibolite/calc-silicate rocks/marble, schist, and metasiltstone. The protoliths for these rocks are sedimentary, tuffaceous and plutonic rocks of both Kingston and Brookville terrane affinity. Pressure-temperature conditions obtained by the computer programme TWEEQU display a range of metamorphic conditions. The results given by TWEEQU were used in conjunction with petrographic features to establish a metamorphic history of the area. The first metamorphic event (M1) occurred at pressures of 5.85 to 6.5 kb and temperatures of 420 to 545°C. The second metamorphic event (M2) was a decompression event that was also responsible for the formation of mylonite. This event occurred at conditions of 3.4 to 5.4 kb and 465 to 600°C. A subsequent retrograde metamorphic event resulted in chloritization in many samples. The Pocologan metamorphic suite formed during the transpressive juxtaposition of the Kingston and Brookville terranes, probably during the Silurian and Devonian.
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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 | 0.000 |
| Scholarly communication | 0.000 | 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".