Exhumation and incision history of the Torngat Mountains, northern Labrador and Quebec, Canada, using apatite (U-Th)/He thermochronology
Bibliographic record
Abstract
Apatite (U-Th)/He thermochronological data provide new insights into the exhumation history of the Torngat Mountains, which are located in Ungava Peninsula, northern Labrador and Quebec, Canada.Latest Jurassic to earliest Cretaceous rifting resulted in crustal extension and opening of the Labrador Sea, causing westward tilting and exhumation of the Labrador continental margin.Post-rift erosion and incision led to the formation of significant topographic relief in the Torngat Mountains.Thermal modeling of apatite (U-Th)/He thermochronological data from a vertical sample transect indicates that rapid cooling starting at ~140-150 Ma, which closely coincides in age with independent geological evidence for initial rifting in the area.Apatite (U-Th)/He ages along an E-W transect, which was collected perpendicular to the Torngat Mountains and the Labrador coast, record differential extensional and erosional exhumation diminishing westwards towards the interior of Ungava Peninsula.Ages near the Labrador coastline are as young as ~ 78 Ma and are significantly younger than the timing of onset of initial rifting (~140-150 Ma); this suggests significant amounts (~1-2 km) of post-rift erosion and incision along the eastern continental margin of the Labrador Sea.West of the Torngat Mountains, along the E-W transect, apatite (U-Th)/He ages also show evidence of substantial post-rift erosion likely related to Mesozoic and Tertiary fluvial erosion or to Pleistocene continental glaciation.Two constant-elevation N-S transects collected parallel to the Labrador coast show apatite (U-Th)/He ages that mimic the larger scale topographic features of the area, such as major rivers and fiords, indicating a deflection of shallow crustal isotherms due to post-rift development of highamplitude topography.Additional numerical modeling is required to refine the timing and spatial magnitude of post-rift erosion in more detail.
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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) | 0.001 | 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 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".