Controls on Asymmetric Continental Crustal Thinning to Symmetric Mantle Exhumation at Magma‐Poor Rifted Margins: Processes Constrained by the West Iberia‐Newfoundland Conjugate Margins
Bibliographic record
Abstract
Abstract Observations indicate that the Iberia‐Newfoundland conjugate margins, a typical example of magma‐poor rifted margins, exhibit a transition from asymmetric continental crustal thinning to symmetric exhumation of the mantle. In this study we use 2‐D thermo‐mechanical models of continental rifting to seafloor spreading to try to elucidate the cause of this transition. Our numerical model integrates grain‐size dependent viscous rheology in the mantle and accounts for hydrothermal cooling along shear zones. Our findings reveal that besides the well‐accepted role of strain‐weakening, two other factors affect asymmetric continental thinning: crustal density, which directly affects horizontal crustal buoyancy; and lower crustal rheology, which primarily influences the evolution of lithospheric strength. Furthermore, the results indicate that the extension rate is the primary parameter governing fault spacing during mantle exhumation. Hydrothermal cooling efficiency along the shear zone increases the strength of the faults, thereby leading to a reduction in the mantle fault offset. Only when the ratio of energy available for deformation that is diverted into reducing the grain size is moderate will the grain size along the shear zone be significantly smaller than that in the surrounding area, thereby producing significant viscous strain weakening and large fault offsets. Our reference model successfully replicates the structural characteristics of the Iberia‐Newfoundland conjugate distal margins. Although direct comparison has been made only with those margins, the similarity between modeled structural features with those observed in other magma‐poor rifted margins suggests a substantial potential for the generalized application of our modeling insights.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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 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".