Petrography, geochemistry, and Nd isotope systematics of metaconglomerates and matrix-rich metasedimentary rocks: implications for the provenance and tectonic setting of the Labrador Trough, Canada
Bibliographic record
Abstract
The New Quebec Orogen consists of a supracrustal belt that was reworked when the Superior Craton collided with the Core Zone terrane during the Paleoproterozoic Trans-Hudson Orogeny. Within the New Quebec Orogen, the Kaniapiskau Supergroup can be divided into four terrigenous lithotypes metamorphosed at low-grade: one set with greater compositional and textural sedimentary maturity classified as quartz arenites and subarkoses, and another set with lower textural maturity classified as feldspathic wackes and mudrocks. In contrast, the Laporte Group includes homogeneous lithotypes represented by feldspathic and lithic wackes with a range of matrix contents metamorphosed at low to medium grade. The Kaniapiskau Supergroup rocks have a wide range of SiO2 and Al2O3 contents (SiO2/Al2O3 = 3.7–51) compared to the restricted compositional range of the Laporte Group rocks (SiO2/Al2O3 = 4.4–6.8). In general, the geochemical variations in both formations of the Laporte Group are within the range of the main clast varieties from basal metaconglomerates, although the Deborah Formation (top unit) records higher TiO2, P2O5, MgO, and Ni contents and high Cr/Th, Co/Ba, Th/U, and Rb/Sr ratios indicating additional mafic sources. Our results support the hypothesis that the Kaniapiskau Supergroup was deposited along an intraplate continental margin with predominantly recycled (εNd(1.87Ga) –12) Paleoarchean sources (TDM 3.2 Ga). In contrast, the Laporte Group marks the transition from a continental forearc (Grand Rosoy Fm.) with a typical juvenile source, including granitic clasts (εNd(1.83Ga) –0.1 to +3.1), to a wedge-top depozone (Deborah Fm.) in the context of a collisional proforeland basin. This syncollisional sedimentary environment is characterized by the presence of old crustal components (εNd(1.83Ga) –4.4 to –9.1).
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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 | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| 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".