Investigating the generation of transport-parallel gradients in ductile strain and kinematic vorticity in the footwalls of metamorphic core complexes: Insights from the Northern Snake Range, Nevada, USA
Bibliographic record
Abstract
Several metamorphic core complexes exhibit structural asymmetry in their exhumed footwalls, with ductile strain, crystallographic preferred orientation (CPO) intensity, and/or mean kinematic vorticity (W m ) increasing in the direction of detachment fault displacement. Here, we investigate the Northern Snake Range metamorphic core complex in Nevada, to explore the processes that are the most influential for generating transport-parallel strain gradients in detachment fault footwalls. Eocene-Oligocene tectonic strain (Rs), lineation-parallel extension, and foliation-normal thinning in the Northern Snake Range increase eastward from 1.5-1.6 to 240-820, 25-30% to 1,400-2,400%, and 15-21% to 93-95%, respectively (assuming no volume change). CPO intensity parameters (cylindricity and J PF index) increase eastward from 0.45 to 0.90-0.95 and 1.40 to 2.64-6.40, respectively, and average W m increases eastward from 0.26-0.40 (72-82% pure shear) to 0.77-0.83 (56-63% simple shear). Restoration of a strain model supported by a range-wide cross-section defines 17.9 km (470%) of Eocene-Oligocene ductile extension. Published footwall cooling histories demonstrate an eastward progression of exhumation-related cooling, driven by unroofing via top-down-to-ESE displacement on the master detachment. This progressive unroofing resulted in an eastward increase in the residence time of quartz-rich footwall rocks at temperatures above ∼300 °C (and thus a longer ductile strain history on the eastern side of the range), which we interpret was a 1 st -order factor for generating the eastward increases in strain, CPO intensity, and W m . The Northern Snake Range is an excellent case study that demonstrates the potential for generation of pronounced transport-parallel structural asymmetry in metamorphic core complexes that are exhumed by high-displacement detachment faults.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".