Tectono-thermal evolution of deep crust in a Mesoproterozoic continental collision setting: the Manicouagan example
Bibliographic record
Abstract
High-pressure metamorphic rocks in continental collision belts provide important information on the orogenic evolution of deep crust. In the Grenville Province, a prime example is the Manicouagan Imbricate Zone (MIZ), a Mesoproterozoic crustal section that was metamorphosed up to 1800 MPa and 850-950°C at ~1050 Ma. High temperatures and the presence of synmetamorphic within-plate tholeiitic gabbro intrusion in the MIZ attest to thermal perturbation during burial and emplacement of mantle-derived melts, consistent with thinning of lithospheric mantle. Subsequently, the MIZ was extruded by a combination of northwest-directed thrusting over a crustal-scale ramp and extension at higher crustal levels. In the middle MIZ, extension was coeval with thrusting, but perpendicular to the thrust direction, and was apparently controlled by ductility contrasts between slices. In contrast, the highest levels show evidence of southeast-directed extension, i.e., of opposite sense to the thrust direction, that postdated thrusting within the MIZ. This episode was followed by renewed northwest-directed thrusting of medium-pressure Mesoproterozoic units over the MIZ, and then by final southeast-directed extension. Overall configuration of the MIZ was achieved between ~1040-990 Ma and is consistent with outward propagation of the orogen. Alternating periods of thrusting and extension displacement are a likely result of adjustments permitting maintenance of dynamic equilibrium within the advancing stack. The tectonothermal characteristics of the MIZ allow comparison between the Grenville Province and younger, thermally perturbed orogens (i.e., Variscan Belt) and may be the final product of a Tibetan Plateau style evolution.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".