Geochronology, petrogenesis, and mineralization potential of the syenogranites in the Yama fluorite deposit, Tataleng granitic batholith, Qilian Orogen, NW China
Bibliographic record
Abstract
The Yama fluorite deposit in the Qilian Orogen in NW China is characterized by predominant granitic magmatism and fluorite mineralization. The wall rocks hosting the fluorite–quartz veins in the Yama area consist of the Yama porphyritic syenogranite and the Wulandawu syenogranite. In this study, the major and trace element compositions, zircon U–Pb ages, and zircon Hf isotopes and trace element compositions were investigated. Two samples for the Yama porphyritic syenogranite yielded weighted mean 206Pb/238U zircon ages of 440.7 ± 4.8 and 447.9 ± 6.0 Ma, and one sample for the Wulandawu syenogranite yielded a weighted mean 206Pb/238U zircon age of 441.2 ± 5.0 Ma, all of which indicate a Late Ordovician to Early Silurian crystallization age. Geochemically, both syenogranites are peraluminous, with high alkali contents, low Zr + Nb + Ce + Y contents, relatively low (K2O + Na2O)/CaO ratios, and high Rb/Sr and Rb/Ba ratios, suggesting that they are fractionated S-type granites. They have zircon εHf( t) values of −14.9 to −4.4 and −12.2 to −4.5, respectively, suggesting that they were derived from the partial melting of pelitic-rich sources within the relatively shallow Paleoproterozoic reworked crust. The detailed geochronological and geochemical data suggest that the studied syenogranites were emplaced in a post-collisional setting related to the closure of the South Qilian Ocean. Finally, they have relatively low quantitative oxygen fugacity values, indicating relatively reduced redox states, but their very low zircon Ce4+/Ce3+ ratios, low whole-rock K/Rb ratios, relatively high Nb/Ta ratios, and low Zr/Hf ratios suggest that they are not likely to form important W–Sn deposits and related fluorite deposits.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".