Chemical, Isotopic, and Textural Characteristics of Diamond Crystals and Their Mineral Inclusions from A154 South (Northwest Territories), Lynx (Quebec), and Kelsey Lake (Colorado): Implications for Growth Histories and Different Mantle Environments
Bibliographic record
Abstract
Parcels of diamond crystals from the A154 South kimberlite diatreme, Northwest Territories (n=281), and the Lynx kimberlite dyke, Quebec (n=6598) were examined in terms of colour, size, morphology, and UV fluorescence (A154 South samples only). A subset of stones from each parcel (A154 South: n=60, Lynx: n=20) were cut and polished to expose internal zonation and mineral inclusions. Exposed primary mineral inclusions were quantitatively analyzed for major elements by EMPA.\n\nDiamond crystals from the Kelsey Lake kimberlite diatreme, Colorado (n=20), were cut into plates and analyzed for nitrogen aggregation states by FTIR. Twelve of these stones were then analyzed with further subsets from A154 South (n=18) and Lynx (n=16) for carbon isotope ratios and nitrogen abundances by SIMS. Every diamond crystal cut and polished had its internal zonation imaged with CL.\n\nMineral inclusion data from A154 South and Lynx show that the mantle keel of the Slave craton is slightly less depleted than that of the Superior craton, and both are less depleted than those of the Kaapvaal and Siberian cratons. Equilibration conditions plot on hotter geothermal gradients (surface heat flows ~42 mW/m2) than for those of typical Archean cratons (≤40 mW/m2). Equilibration temperatures (~1150-1250°C) are ~100-200°C hotter than previously reported from Kelsey Lake (~1020°C).\n\nKelsey Lake and A154 South samples have carbon isotope ratios and nitrogen contents typical of most diamond populations worldwide. Diamond crystals from Lynx are entirely different, consisting of mostly Type II diamond with δ13C (vs. PDB) values from approximately -3.6 ‰ to +1.7 ‰. These 13C-enriched samples are suggested to be the result of extreme Rayleigh fractionation of diamond from a carbonate fluid and possibly input of carbon sourced from subducted abiotic oceanic crust. Also notable is that growth trends (δ13C-[NT]) for most of the samples studied show little or no consistency with published fractionation models.
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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 | 0.000 |
| 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 | 0.000 | 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 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".