Paleoproterozoic reworking of an Archean thrust fault in the Hearne domain, Western Churchill Province: UPb geochronological constraints
Bibliographic record
Abstract
The nature, timing and control of Archean crustal architecture on the distribution of Proterozoic reworking in Western Churchill Province are investigated in the Yathkyed Lake area, central Nunavut. The Tyrrell shear zone (TSZ) marks the boundary between the northwestern and central Hearne subdomains, respectively, in the hanging wall and footwall. Metamorphism and deformation in the hanging wall are ca. 2.662.50 Ga. Two episodes of metamorphism are recorded in a foliated granodiorite in the footwall, at 1818+52 and 1827 ± 5.6 Ma. The latter age is interpreted as the time of amphibolite-facies metamorphism and deformation in the footwall. A crosscutting dyke provides a minimum age of 1818 ± 2 Ma for this metamorphism and deformation. The TSZ is dominated by dextral oblique-slip shear fabrics. A suite of leucogranite dykes provide a maximum age of 1816 ± 2 Ma for dextral shearing. Dextral deformation is bracketed between 1815 ± 2 and 1811 ± 1 Ma, the ages of two other granitoid dykes. In an area of low dextral strain, there are proto-sheath folds related to Neoarchean thrusting. Paleoproterozoic transtensional shearing in the TSZ was localized along a preexisting late Archean thrust fault. The prior existence of this structure resulted in localization of penetrative Paleoproterozoic deformation in its footwall. This domain of high-grade Proterozoic deformation was uplifted in a regional, antiformal, metamorphic culmination, in part, by dextral-normal shearing along the TSZ. Penetrative basement deformation at depth played a role in transmitting farfield stresses related to the Trans-Hudson Orogen into its hinterland.
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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 | 0.001 |
| 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) | 0.002 | 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".