Evaluation of Nd isotope data for the Grenville Province of the Laurentian shield using a geographic information system
Bibliographic record
Abstract
The Grenville Province of eastern North America contains a record of continental growth on the southeast margin of Laurentia through much of the Proterozoic Eon, and this growth history can be charted using Nd model age mapping. This paper describes the first use of a geographic information system (GIS) to evaluate such data. The Grenville Province of Ontario and western Quebec, Canada, was chosen for study because there is a lack of agreement on the location of major geological boundaries, whereas the high density of Nd isotope sampling allows precise solutions to be proposed. Two different contouring algorithms, triangulated irregular networks (TIN) and inverse distance weighting (IDW), were first evaluated to select the best geospatial analysis method and parameters for visualizing and evaluating Nd model age distributions. The method chosen (IDW at a power of 6), was then used to test the location of two major boundaries that separate rocks of different crustal formation age, the Grenville-age Allochthon Boundary thrust and the pre-Grenvillian Archean-Proterozoic boundary. GIS analysis was initially performed using published data, after which further sampling was performed to improve coverage of problem areas. The GIS analysis was then repeated, incorporating Nd data for over 80 new localities. The result is a more reliable and accurate map of terrane boundaries in the southwest Grenville Province, which is a critical step in reconstructing the Proterozoic evolution of the southeast margin of Laurentia.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.004 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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
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".