Field observations, mineralogy and geochemistry of Middle Devonian Ni-Zn-Mo-PGE hyper-enriched black shale deposits, Yukon
Bibliographic record
Abstract
Hyper-enriched black shale (HEBS) deposits are a globally significant repository of base, strategic and precious metals. Some of the best examples of this deposit type are hosted within Devonian shales in northern Yukon. Hyper-accumulations of Ni-Zn-Mo-platinum group elements (PGE) occur in a thin (<10 cm) stratiform and stratabound layer that is widespread geographically (10 000s km2). Despite decades of research, basic questions surrounding the precious metal mineral host(s), age and process(es) responsible for hyper enrichment remain unresolved. Preliminary laser ablation-inductively coupled plasma-mass spectrometry data for the various base metal sulphide minerals within the HEBS mineralization reveal that vaesite is the principal PGE host (up to 10 ppm Pd, Pt) at the Nick deposit, whereas the fine-grained pyritic matrix hosts PGE (up to 3 ppm Pd and 10 ppm Pt) at the Peel River locality. Conodont biostratigraphy, determined using x-ray microcomputed tomography, gives a Givetian (late Middle Devonian) age that compares well with the regional stratigraphic framework, and is the first ever reported for the HEBS mineralization in Yukon. Finally, recent fieldwork has revealed the occurrence of up to three discrete stacked stratigraphic HEBS layers. Collectively, these data indicate an ambient paleoenvironment in which highly efficient scavenging of metals and metalloids from seawater operated in tandem with extremely low rates of clastic sedimentation and highly efficient organic matter remineralization. Similar topologies between continental crust-normalized PGE patterns for seawater and HEBS layers support the conclusion that metals and metalloids predominantly originated from ambient seawater.
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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) | 0.002 | 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 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".