Geodynamic models of mature continental collision: Evolution of an orogen from lithospheric subduction to continental retreat/delamination
Bibliographic record
Abstract
The behavior of deep lithospheric processes in continental collision are frequently speculated on, but poorly understood. In this study we build on previous work to explore the styles of continental lithosphere deformation during mature collision where ∼1800 km of convergence has been accommodated by horizontal shortening. We conducted a suite of numerical geodynamic experiments that test the sensitivity of mature continent collision to varying mantle lithosphere density, mantle lithosphere yield stress, lower crustal strength and to the presence of phase change‐related density changes in the lower crust (i.e., eclogitization of mafic lower crust). The models suggest that the early stages of collision are accommodated by subduction of lower crust and mantle lithosphere along a discrete shear zone beneath the overriding plate. Following this initial stage of subduction, the subducting lower crust and mantle lithosphere can retreat from the collision zone, permitting the sub‐lithospheric mantle to upwell and intrude the overriding plate. As a result, the lower crust and mantle lithosphere of the overriding plate delaminate from the overlying crust. With local isostatic adjustment, subduction‐ and delamination‐driven crustal processes plateau‐like uplift occurs. The sub‐crustal evolution also causes bands of syn‐convergent crustal extension to develop. In models with a rheologically weaker lower crust, surface crustal response to the deep lithosphere dynamics becomes more diffuse. As an example, the numerical experiments satisfy a number of surface observables of the Himalayan‐Tibetan orogen, namely: (1) the current general mantle lithosphere architecture as defined by seismic analyses; (2) the long‐wavelength plateau uplift of the western Tibetan Plateau; (3) the surface heat flow measurements in India, the Tethyan Himalaya, Qiangtang and in Qaidam basin; and (4) the anomalous syn‐convergent extension in the southern portion of the orogen.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".