Tonian rift successions in Newfoundland, Canada: a window to late tectonic events in the Mesoproterozoic Laurentian margin
Bibliographic record
Abstract
Basement rocks in the Humber terrane of the Appalachian Orogen record the last stages in the history of the Mesoproterozoic Laurentian margin in Canada. These stages were revealed by recent work in the East Pond Metamorphic Suite on the western Baie Verte Peninsula, Newfoundland, where two Tonian bimodal volcaniclastic-sedimentary successions were recognized (Pine Pond successions). The older, ca. 980 Ma succession, contains detrital igneous zircon and titanite (ca. 1160–1057 Ma) presumably derived from the Mesoproterozoic Laurentian margin, while the younger, ca. 950 Ma succession, contains 980 Ma detrital igneous zircon and titanite. Although metamorphosed to eclogite facies during the assembly of the Appalachian Orogen, the successions preserve protolith features and geochemical data that indicate melt likely originated in an extensional setting. The new ages integrated with geochemical and Sm–Nd isotopic data suggest that the felsic volcaniclastic units of the Pine Pond successions are related to 975–950 Ma granitic plutons in the Pinware terrane of the eastern Grenville Province in southeastern Labrador. These new data solidify a previous interpretation that the Pine Pond successions were deposited at the continental apex of the Asgard Sea and that the Pinware terrane intrusions are a part of this event. Furthermore, these new Tonian ages for rift-related strata call into question the interpretation of Ediacaran depositional ages for clastic sequences in the northern Appalachian Orogen, with youngest detrital zircons that are Tonian, and show that the tectonic evolution of the Mesoproterozoic Laurentian margin in Canada is more complex than previously known.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".