Re–Os dating of pyrite and mineral chemistry of magnetite from the Yamansu Fe deposit, Xinjiang, northwestern China
Bibliographic record
Abstract
The Yamansu iron deposit, hosted in submarine volcanic rocks, is located in the Aqishan–Yamansu Fe–Cu metallogenic belt of eastern Tianshan, Xinjiang. New pyrite Re–Os and pyroxene diorite intrusion ages and the chemistry of magnetite constrain the origin of the deposit. The Yamansu orebodies display banded or lenticular forms and sharp contacts with marble and garnet skarn. Pyrite associated with magnetite from hydrothermal massive ores has a Re–Os isochron age of 320.3 ± 9.1 Ma, which is consistent with the Carboniferous age of volcanic rocks. However, the pyroxene diorite age (252.1 ± 3.7 Ma) is obviously younger than the mineralization age, implying no temporal relationship between mineralization and intrusion. Magnetite samples from different ores in the Yamansu deposit are suggested to have a magmatic–hydrothermal origin. The magmatic primary magnetite is rich in TiO2 and poor in SiO2, MgO, and CaO, similar to magnetite from Kiruna type deposits. The hydrothermal magnetite is rich in FeO, CaO, and SiO2 but poor in TiO2 and shows oscillatory zoning. Moreover, magmatic and hydrothermal magnetite samples show different characteristic normalized rare earth element and trace element patterns. A combination of ore fabrics, discrimination diagrams, and normalized patterns for magnetite samples can reflect the magmatic–hydrothermal process. The Yamansu iron deposit is spatially and temporally associated with Carboniferous volcanism, and we propose that the magmatic magnetite ores were derived from iron-rich melt through melt immiscibility. The residual iron-rich magma ascended and erupted along with hydrothermal activity; then moderate to large amounts of hydrothermal massive, banded, or disseminated magnetite formed with skarns.
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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) | 0.000 | 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".