Weakening mechanisms in reactivated crustal-scale \nfaults: the Dover Fault Shear Zone, Newfoundland
Bibliographic record
Abstract
Crustal-scale faults have been argued to represent relative and absolute zones of weakness in \ncomparison to the intact continental crust due to their preferential reactivation and accumulation of \nstrain. In order to understand the long term deformation behaviour of crustal-scale faults, it is \nimportant to study how deformation processes in the mid-crustal frictional-viscous transition zone \n(FVTZ) can alter the frictional strength of the crust. Exhumed fault rocks from the Dover Fault \nShear Zone (DFSZ) record evidence of long-term weakening mechanisms. The DFSZ in north \neastern Newfoundland represents a major Appalachian terrane boundary that separates highly \nmetamorphosed gneisses in the Gander Zone from deformed volcanics in the Avalon Zone. \nAnalysis of field data, hand specimens and microstructures revealed a series of progressively lower \ntemperature, overprinting deformation phases in increasingly narrower, localised shear zones. The \nfault rocks show increasing strain towards the boundary as grain size reduces, fabric intensifies and \nfolds tighten and become progressively curvilinear. Evidence of fluid influx during deformation \nincludes microstructures that are indicative of fluid assisted diffusive mass transfer (DMT) and a \nhigh degree of phyllonitization of the fault rocks. \nIncreasing strain and structural overprinting towards the centre of the shear zone is indicative of \nstrain weakening and the later brittle faulting that has reactivated the DFZ is evidence of this long \nterm weakening. The most important weakening mechanisms to have affected the DFSZ arose from \nthe syn-tectonic influx of fluids, including both hydrous fluids and magmas, as this led to \nproduction of phyllosilicates in reaction softening, the development of interconnected weak layers \nand thermal perturbations in the fault zone. These processes produced a highly localised network of \nshear zones whose frictional strengths were permanently reduced, thus impacting the long-term \nstrength and behaviour of the fault in the upper crust.
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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 | 0.001 |
| Science and technology studies | 0.001 | 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
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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".