Provenance of the Newfoundland Appalachian foreland basins
Why this work is in the frame
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Bibliographic record
Abstract
The tectonic history of the Appalachian orogen is recorded in the adjacent foreland. Offshore seismic data suggest that an initial, Middle Ordovician foreland basin was filled by sources in Newfoundland, whereas the Late Ordovician foreland basin was loaded and filled by sources to the SW, in the Québec segment of the orogen, where NW-vergent Taconian arc-continent collision may have continued later than in Newfoundland. We test this hypothesis using U/Pb ages of detrital zircon within foreland basin successions in western Newfoundland. Previously published results from the oldest foreland succession, the Middle Ordovician Goose Tickle Group, demonstrate ages similar to units preserved with the Humber Arm Allochthon, emplaced during Middle Ordovician Taconic orogenesis, including a predominant Paleoproterozoic peak at 1.85 Ga. In this study we investigated U/Pb geochronology of detrital zircon from younger foreland successions from Upper Ordovician to Devonian. The largest proportion of analyses within all foreland successions fall between 0.95 and 1.3 Ga, with largest peaks occurring between 1.0 and 1.1 Ga, typical of zircon derived from the Grenville Orogen. Earlier Mesoproterozoic and Paleoproterozoic ages range from 1.3 to 2.0. The abundance of Mesoproterozoic grains and conspicuous lack of 1.85 Ga Paleoproterozoic zircon in the overlying Upper Ordovician Long Point Group and latest Silurian to Early Devonian Clam Bank Formation indicates that these sediments were not derived from units within the Humber Arm Allochthon. Probability density plots of continental margin units in the Québec/New England segment of the orogen demonstrate a similar strong Mesoproterozoic and weak Paleoproterozoic signature, suggesting derivation of the Long Point Group from the Québec segment of the orogen. Within the mid-Paleozoic Clam Bank - Red Island Road succession, typical Gondwanan ages are absent and 1.0 Ga grains derived from the Grenville Orogen are abundant. This is consistent with underthrusting of the Gondwanan microcontinents Ganderia and Avalonia during Salinic and Acadian orogenesis. Only Mesoproterozoic zircon grains were found in the Early Devonian Red Island Road Formation, consistent with derivation from Mesoproterozoic Grenville massifs in western Newfoundland or Cape Breton Island which were exhumed during Devonian Acadian inversion.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 it