Lithostratigraphy and Geochemistry of the High-Grade Metasedimentary Rocks in the Thompson Nickel Belt and Adjacent Kisseynew Domain, Manitoba: Implications for Nickel Exploration
Bibliographic record
Abstract
Exploration for nickel in the Thompson nickel belt is focused on specific paragneiss units within the Paleoproterozoic sedimentary and volcanic cover succession (Ospwagan Group) on the northwestern margin of the Archean Superior craton. These units host ultramafic bodies and all significant nickel deposits in the Thompson nickel belt. Knowledge of the lithostratigraphy is therefore essential for finding the units with the highest potential for the discovery of new nickel deposits. This is made practical by a distinctive stratigraphic succession with numerous marker units, including metamorphosed quartzite, carbonate, pelite, iron formation, and graywacke, as summarized in this paper. However, the sedimentary rocks are generally highly deformed and metamorphosed, making the recognition of some units difficult and their sedimentary origin obscure. To better recognize the sedimentary protoliths of orehosting and related units, a simple plot of SiO 2 versus Al 2 O 3 is used to estimate the approximate proportions of siliciclastic and chemical sedimentary components. This demonstrates that much of the succession, which was previously considered to be derived from calcareous and ferruginous chemical sediments, is a hybrid containing a substantial siliciclastic component, thus explaining the present mineralogy and geochemistry and assisting in the recognition of units at various metamorphic grades. Extended-element plots, using the most abundant metapelite unit in the Ospwagan Group as the normalizing factor, show a common provenance for the entire group. They also illustrate a clear difference between the Ospwagan Group and the underlying basements gneiss and allow the Ospwagan Group to be distinguished from petrographically similar but economically barren, younger paragneiss units of the Burntwood and Grass River groups. Unlike the Ospwagan Group, the younger units, which predominate in the Kisseynew Domain adjoining the Thompson nickel belt, were derived mainly from an exotic Paleoproterozoic arc-related source and therefore have a different geochemical signature. This geochemical difference can be utilized in areas of sparse geologic information, such as beneath Phanerozoic or glacial cover, where initial exploration drilling tests new geophysical targets. Combined litho- and chemostratigraphy improve insight into basin evolution, which probably occurred on a ca. 2 Ga passive continental margin or shelf. The ca. 1880 Ma maficultramafic magmatism related to the nickel deposits may have formed in a different tectonic environment, possibly in a continental back arc associated with a recently proposed episode of felsic calc-alkaline plutonism.
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 distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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 teacher head, 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".