Net evolution of subglacial sediment transport in the Quebec-Labrador Sector of the Laurentide Ice Sheet, Quebec and Newfoundland and Labrador
Bibliographic record
Abstract
The interior of the Laurentide Ice Sheet (LIS) had a dynamic polythermal base. However, the subglacial thermal organization of the LIS and its evolution throughout glaciation are poorly constrained. Specifically, the net effect of ice divide migration on subglacial processes and the resulting landforms and sediments remains poorly understood. The results of a regional-scale till sampling program within the interior of the Quebec-Labrador sector of the LIS were used to explore dispersal patterns across a region known to have experienced ice divide migration. Indicator mineral and clast lithology analysis, coupled with multivariate analysis of the till matrix geochemistry, were used collectively, and evaluated within the context of the relative ice flow chronology and subglacial thermal evolution to augment our understanding of how ice divide migration impacts subglacial erosion and sedimentary processes. Indicator minerals (e.g., goethite and orthopyroxene) and clasts (e.g., iron formation clasts from the Labrador Trough) form glacial dispersal patterns that are consistent with the earliest northeast-trending ice-flow phase identified in the region. This early ice-flow phase produced and transported till across the entire study area (> 175 km). However, till matrix geochemistry shows a strong relationship with the local underlying bedrock, especially the major oxides. This relationship is relatively common in areas of thin till cover and resistant bedrock lithologies. The results also indicate that following the northeast ice-flow phase, erosion and till production became more localized, without considerable transport in a single sustained direction. These results are consistent with a transition to more sporadic warm-based conditions and ice divide migration, as ice sheet reconstructions indicate, and are supported by targeted 10Be data from erratics and bedrock surfaces. There are also spatial relationships between the dispersal of fresh or re-entrained debris and paleo-ice streams identified in the landform record, as evidenced by the dispersal of indicator minerals. The reworking of previously dispersed material during subsequent ice-flow phases resulted in complex dispersal patterns across the study area. These results provide important insights for ice sheet modelling and future mineral exploration programs in inner ice sheet regions of the LIS and demonstrate the importance of a thorough understanding of ice-flow history.
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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 | 0.000 |
| 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".