Mechanisms of ore formation in Silurian (Caledonian) scheelite deposits of the Nanling Range, South China: A case study from the Pingtan W deposit
Bibliographic record
Abstract
The Pingtan scheelite deposit is a newly-discovered Caledonian W deposit situated in the northwestern portion of the Miao’ershan granitic batholith in the Nanling Range. The W mineralization can be divided into three stages, the altered granite-scheelite stage (I), the quartz-scheelite stage (II) and the quartz-sulfide stage (III). This contribution characterizes the mechanisms of ore formation of the deposit using fluid inclusion microthermometry, H-O isotopes, and in situ S isotopes. Fluid inclusion microthermometry demonstrates that the scheelite mainly formed at moderate to high temperatures (∼260–380 °C for stage I and ∼ 240–300 °C for stage II). The inclusions were trapped at maximum pressures of ∼ 140 MPa, which corresponds to a maximum depth of ∼ 5.3 km. Homogenization temperatures of the inclusions decrease slightly from stage I to stage II mineralization, and more drastically from stage II to stage III, whereas their salinity decreases gradually during the entire mineralization process. Raman spectroscopy indicates that fluid inclusions in stages I and II contain CO2, CH4, and N2, whereas those in stage III mainly contain H2O. The presence of native bismuth, pyrrhotite, and marcasite, and the presence of CH4-bearing fluid inclusions suggest reduced ore-forming conditions during Stages I and II. The δ34SCDT value (+0.8 to + 5.3 ‰, average 3.2 ‰) of sulfides and the δ18Ovsmow value of ore-bearing quartz, which decreases from Stage I (δ18Ovsmow = +5.1 to + 6.3 ‰) to Stage III (δ18Ovsmow = − 1.5 ‰ to + 0.6 ‰), as well as the presence of abundant fluid inclusions with daughter minerals in the first two stages, supports a magmatic origin for the ore-forming material, with exogenic fluid input after the tungsten mineralization stage. Based on the results of this contribution, boiling may be the dominant mechanism for the formation of W deposits in the Nanling Range.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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 teacher head, 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".