LKZ-1: A New Zircon Working Standard for the In Situ Determination of U–Pb Age, O–Hf Isotopes, and Trace Element Composition
Bibliographic record
Abstract
This study introduces a new zircon reference material, LKZ-1, for the in situ U–Pb dating and O–Hf isotopic and trace element analyses. The secondary ion mass spectrometric analyses for this gem-quality single-crystal zircon yielded a weighted mean 206Pb/238U age of 572.6 ± 2.0 Ma (2σ, n = 22, MSWD = 0.90), with moderately high U concentrations (619 ± 21 ppm, 1 SD), restricted Th/U ratios (0.146 ± 0.002, 1 SD), and negligible common Pb content (206Pbc < 0.2%). A comparable 206Pb/238U age (570.0 ± 2.5 Ma, 2σ) was produced by the isotope dilution-thermal ionization mass spectrometry. The secondary ion mass spectrometric and laser ablation-assisted multiple collector inductively coupled plasma mass spectrometer analyses respectively showed that LKZ-1 had little variation in O (δ18OV-SMOW = 10.65 ± 0.14‰; laser fluorination value = 10.72 ± 0.02‰; 1 SD) and Hf (176Hf/177Hf = 0.281794 ± 0.000016, 1 SD) isotopic compositions. LKZ-1 was also fairly homogeneous in its chemical composition (RSD of laser ablation ICPMS data ≤ 10%), displaying a relatively uniform chondrite-normalized rare earth element pattern ((Lu/Gd)N = 31 ± 3, Eu/Eu* = 0.43 ± 0.17, Ce/Ce* = 44 ± 32; 1 SD). These consistencies suggest that the LKZ-1 zircon is a suitable working standard for geochronological and geochemical analyses.
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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 | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.004 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.003 |
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".