Mineralization timing and genesis of the Dongxiang stratabound Cu-Mo-W deposit in the Qinhang metallogenic belt (South China): Constraints from U-Pb and Re-Os geochronology and sulfur isotopes
Bibliographic record
Abstract
Abstract The Qinhang metallogenic belt is one of the important copper polymetallic metallogenic belts in eastern China. In this belt, many ore deposits host high-grade stratabound copper ore bodies. However, there has been considerable controversy over their origins. The key to the dispute over the origin of the deposits is the lack of precise metallogenic age constraints, which seriously restricts our understanding of the metallogenetic regularity of copper polymetallic deposits in the Qinhang metallogenic belt. To address the controversies regarding the genesis of these types of ore deposits in the Qinhang metallogenic belt, this study focuses on Dongxiang, a representative stratabound, copper-rich deposit in South China. Molybdenum mineralization was discovered through detailed field geological surveys and drilling. This paper reports Re-Os dating for molybdenite in different occurrences for the first time. High-precision Re-Os dating of molybdenite in the Dongxiang deposit shows that the weighted ages of molybdenite in different occurrences are relatively consistent, ranging from 160.4 Ma to 158.7 Ma. The isochron age obtained for all samples is 159.6 ± 0.8 Ma, which is consistent with the weighted mean age of 159.6 ± 0.9 Ma. The hydrothermal apatite, closely associated with the chalcopyrite and bornite mineralization in stratabound copper ore bodies, yielded a lower intercept age of 156.4 ± 1.5 Ma. Zircon U-Pb ages of granodiorite porphyry and granite porphyry are 157.5 ± 0.58 Ma and 153.9 ± 0.63 Ma, respectively. Therefore, the Dongxiang deposit’s rock-forming and mineralization age is concentrated between 160 Ma and 154 Ma. Sulfur isotope compositions of sulfides in stratabound copper ore bodies show a narrow range of δ34S values, from 0.1‰ to 1.85‰, which is consistent with a magmatic origin. Combining Cu-Pb-H-O isotope and previous studies, we comprehensively propose that the Dongxiang is a porphyry-distal hydrothermal Cu-Mo-W polymetallic deposit formed in the Late Jurassic and associated with paleo-Pacific plate subduction. The Qinhang metallogenic belt holds significant potential for porphyry-skarn copper polymetallic deposits, rather than sedimentary exhalative 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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| 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".