The 3-D crustal structure in the Manicouagan region: new seismic and gravity constraints
Bibliographic record
Abstract
Lithoprobe line 55 represents an oblique seismic crossing of tectonic domains in the Manicouagan region of the Grenville Province in eastern Quebec that has provided a basis for construction of a 3-D model of crustal structure. Reprocessing of the seismic profile presented here has enhanced the imaging of prominent, out-of-the-plane reflection zones that originate from high-pressure metamorphic rocks northwest of the line. We show that after conventional migration the apparent dips of out-of-plane reflections can be compared with regional foliation trends, but the reflection orientations, in themselves, provide only weak constraints on the orientation of out-of-plane of reflectors. We describe and implement several graphical techniques to estimate reflector orientation near large bends in the profile. Using a prestack processing technique, we find poorly resolved but shallow dips and approximately eastward strike directions for reflections from Berthé, Hart Jaune, and Tshenukutish terranes near Relais Gabriel. While many of these seismically derived attitude measurements are broadly consistent with existing 3-D structural models, some discrepancies have yet to be fully resolved. The Bouguer gravity field in this area is dominated by several intense anomalies, including the Grenville Front gravity low and the Manicouagan Plateau gravity high. The residual gravity field, obtained by subtracting the predicted anomalies for these features from the Bouguer gravity field, provides evidence in support of a lateral basement ramp.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".