Formation, reactivation and exhumation of the extruded basement wedge in the southern Longmen Shan, eastern Tibetan plateau
Bibliographic record
Abstract
The Longmen Shan (LMS) fold-and-thrust belt in the eastern Tibetan plateau marks the boundary between the Songpan–Ganze terrane and the Sichuan basin. Deformation mechanisms and the mountain building process in the LMS remain unclear. Here we conducted field mapping, structural analysis, 40 Ar/ 39 Ar geochronology of biotite, and re-interpretation of the Wenchuan Earthquake Fault Scientific Drilling borehole data and a seismic reflection profile across the LMS. Our results indicate that a gently dipping LMS extruded wedge overlies the reactivated Yangtze craton. This wedge consists of several rigid Neoproterozoic complexes, bounded by the NW-dipping LMS detachment above and the Yingxiu–Beichuan thrust below. The Yingxiu–Beichuan thrust extends northwestwards to a depth of c. 8 km beneath the Songpan–Ganze terrane. Coeval activation of the top-to-the-NW LMS detachment and the top-to-the-SE Yingxiu–Beichuan thrust in the Early Cretaceous resulted in the extrusion of the LMS wedge from a depth of 10–15 km. The wedge rapidly exhumed through imbricated thrusting along low-strength series since 40–30 Ma. This Cretaceous basement wedge extrusion bridges the time gap between the Late Triassic–Early Jurassic crustal shortening and the Cenozoic rapid exhumation in the LMS, representing a transformation from north–south compression in the Late Triassic–Early Jurassic to east–west compression in the Cenozoic.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".