Diamond in the AtlinNakina region, British Columbia: insights from heavy minerals in stream sediments
Bibliographic record
Abstract
The sources of rare diamonds reported in northwestern British Columbia, southwestern Yukon, and parts of Alaska are enigmatic. We carried out a heavy-mineral survey of 17 streams draining bedrock in the AtlinNakina region in northwestern British Columbia to determine if high-pressure igneous and metamorphic rocks exhumed in the area could be potential sources for the diamond. Heavy-mineral fractions returned flakes of gold but no diamond. The ferromagnetic fractions were examined optically and by electron microprobe analysis of key indicator minerals, namely olivine, orthopyroxene, clinopyroxene, garnet, spinel, and titanite. Detritus from a horizon of coarse pebble conglomerate in the Jurassic Laberge Group south of Atlin is the most likely source of the anomalous diamond. Garnets and pyroxenes in the latter sedimentary unit were derived by rapid erosion of peridotite and eclogite massif bodies exhumed from depths approaching the diamond stability field during collision and Pliensbachian uplift in the northern Cordillera. Evidence is shown for glacial transport of detritus from both the Laberge Group sediments and Neogene volcanics, the latter of which evidently covered a much wider area before the last glaciation.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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 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".