Numerical models of the inversion of half‐graben basins
Bibliographic record
Abstract
We investigate the dynamic evolution of fold and thrust structures which form by compression and inversion of a sequence of half‐graben basins. The choice for a half‐graben geometry is motivated by seismic studies and reconstructions of preinversion geometry of inverted regions, which show that rifting often leads to a series of half‐grabens. To examine the deformational structures which result from basin inversion, we use a two‐dimensional, viscous‐plastic numerical model and start our experiments from a preexisting extensional geometry. We find that synrift and postrift sediments are uplifted in the initial stages of basin inversion. This uplift is accompanied by rotation of the basement blocks beneath the basins. In the postrift sequence new shear zones form which are a continuation of basin‐bounding faults. With continuing shortening, further inversion is more difficult owing to relative strengthening of the half‐graben region. Significant surface erosion facilitates inversion. Back thrusts mainly develop in association with listric basin‐bounding faults and less for planar (domino array) faults. Weak sediments (such as salt or shales) at the base of the basins promote the development of basement shortcut faults. The presence of a postrift decollement layer tends to decouple deformation of the postrift sediments from the material below it. In our model, preexisting weak basin‐bounding shear zones are a requirement for substantial amounts of basin inversion to occur. Our numerical model results display many first order characteristics of examples from nature and analogue studies.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".