Research on the enrichment and mineralization of Nb–Ta elements in alkaline rhyolite of the Early Cretaceous Toudaoqiao deposit, the Great Xing'an Range
Bibliographic record
Abstract
The Toudaoqiao niobium–tantalum (Nb–Ta) deposit is the largest magmatic rock-type rare metal deposit discovered in the Great Xing'an Range. The ore body is hosted in alkaline rhyolite, and Nb–Ta primarily hosted by columbite, magnetite-(Nb), and ilmenite-(Nb). In this study, we present U–Pb zircon ages, Hf isotope date, and whole-rock geochemistry to elucidate Toudaoqiao alkaline rhyolite evolution. Magmatic zircon ages suggest the mineralization occurred in the Early Cretaceous. The positive ε Hf (t) (zircon) values range from 5.50 to 9.61 with T DM2 of 836–574 Ma, as well as the geochemical characteristics of K 2 O/Na 2 O > 1 and Mg # <<40, indicate that the magma originated from the partial melting of Neoproterozoic–Paleozoic newly accreted potassium-rich intermediate-mafic lower crust. During extension of the Great Xing'an Range in the Early Cretaceous, roll-back of the subducting Paleo-Pacific plate triggered upwelling of asthenosphere mantle material to heat and partially melt the lower crust. The parental magma became highly fractionated by the action of F and other volatiles, resulting in enrichment of Nb–Ta in the residual melt, culminating in precipitation of Nb–Ta minerals. A magma source characterized by significant rare element enrichment is the key factor for Nb–Ta mineralization of the Toudaoqiao.
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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 | 0.000 | 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) | 0.001 | 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".