Lithospheric unzipping explaining hot orogenesis during continental subduction
Bibliographic record
Abstract
Phanerozoic accretionary orogens typically contain upper crustal nappes derived from subducted lithosphere - oceanic or continental - that display (ultra-)high-pressure, low-temperature ((U)HP-LT) metamorphism. Surprisingly, such orogens often also contain coeval continent-derived nappes that underwent ‘Barrovian’ (MP-HT) syn-burial metamorphism instead. Here, we show examples from the eastern Mediterranean orogen of such Barrovian units, which were transported at a low angle below the orogenic crust over 150 km or more within ~10 Ma after the inception of their underthrusting. These Barrovian units - the Kırşehir Block, Menderes Massif and Naxos Basal Unit - form the deepest exposed structural levels of the orogen and are still underlain by 20-35 km thick continental crust, but are missing their pre-orogenic lithospheric mantle, which is in steeply subducted slabs instead. We propose that these Barrovian units were accreted by a syn-subduction delamination process dubbed 'lithospheric unzipping', whereby continental crust decoupled around Moho depth from its subducting mantle lithosphere, and underplated the accretionary orogen at low angle, pushed by the slab. The unzipped crust, no longer protected from the asthenosphere by mantle lithosphere, heated up quickly during burial. Continental subduction may thus have three modes: (i) formation of thin (U)HP-LT nappes during subduction of stretched continental margins; (ii) underplating of thicker, MP-HT continental crust by unzipping; and (iii) eventual arrest of continental subduction with the arrival of unstretched continent. Finally, lithospheric unzipping may have been the default during continental subduction in a hotter, younger Earth, possibly explaining enigmatic hot Proterozoic orogenesis, like in the Canadian Trans-Hudson 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".