Stratigraphy, depositional setting, and volcanism of the Letete Formation, Southwestern New Brunswick
Bibliographic record
Abstract
This thesis interprets the geology and lithogeochemistry of part of the Silurian Letete Formation in southwestern, New Brunswick, based on detailed mapping of a 910- m thick section, petrographic analysis of 52 thin sections, and major and REE geochemistry of 11 samples. The mapped Letete section generally represents a shoaling upward sequence. The section is subdivided into three parts. The lowest contains an upward shoaling sequence of subaqueously emplaced mafic pillow flows, pillow breccias, and sheet flows, overlain by subaerially emplaced sheet flows that are interbedded with Surtseyan-style phreatomagmatic tuffs. The middle section contains black and grey siltstones interbedded with felsic volcaniclastic rocks indicating pulses of volcanism separated by periods of relative quiescence. The shallowest water depths occur at the upper 50 m of the section represented by a mafic tuff interpreted to be the result of a shallow water Surtseyan-style eruption. The upper section contains black siltstones interbedded with increasing volumes of felsic volcaniclastic rocks and overlain by massive grey siltstones that are interpreted to record a shoaling upwards deltaic sequence with increasing felsic volcanism. At the top of this section a 360-m thick section of massive and bedded felsic tuff is interpreted to represent steady plinian and waning pulses of subplinian volcanism. Processes of fractionation and crustal contamination account for the decreasing Mg#, increasing ratio of LILE/MORB, and decreasing HFSE/MORB upward in the section. The rocks are bimodal, and the mafic rocks have a within-plate geochemical affinity consistent with the interpretation that volcanism occurred during extension continental rift. This rift may have been the back-arc to the Kingston arc.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.000 | 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 teacher head, 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".