Trace element geochemistry of pyrite in the uraniferous dolostone from Tummalapalle area of the Cuddapah Basin, India: Implications for gold mineralization
Bibliographic record
Abstract
*Corresponding author. • Three generations of pyrite (Py1, Py2, Py3) are identified based on textures and trace element chemistry. • Py1 formed as fine-grained crystals at low temperatures, Py2 formed by recrystallization of Py1, and Py3 formed as euhedral grains during low-grade metamorphism. • Gold occurs as solid solution within arsenian pyrite, with Py3 showing higher gold due to remobilization during early metamorphic recrystallization. • The study highlights the link between pyrite evolution and invisible gold mineralization in the Vempalle dolostone. This study investigates pyrite-hosted gold occurrences within the uraniferous dolostone of the Vempalle Formation, Papaghni Group of the Paleo–Mesoproterozoic Cuddapah Supergroup in southern India. Although the Cuddapah Basin is well known for its stratabound uranium deposits, the mechanisms controlling invisible gold enrichment in pyrite within these carbonates remain poorly understood. Petrographic study of the uraniferous dolostone reveals the presence of sulfide phases like, pyrite and chalcopyrite. On the basis of textural characteristics and trace element distribution, three types of pyrite (Py1, Py2, and Py3) are identified. Py1 is fine-grained and formed during early to syn -diagenetic stages. Py2 originated from the recrystallization of Py1 during late diagenesis and shows coarse-grained, subhedral to anhedral forms. Py3 is subhedral to euhedral in shape, and developed as overgrowths on Py2 during low-grade metamorphic recrystallization and shows higher invisible gold concentration among all the three pyrite types. The Au/As atomic ratios (ranges from 2.6 × 10 −6 to 5.6 × 10 −4 ) plot below the inferred solubility limit for pyrite-hosted gold, suggesting gold occurs in solid solution rather than as free nanoparticles. This study is the first report on the pyrite hosted invisible gold occurrence within the uraniferous Vempalle dolostone of the Cuddapah basin in and around Tummalapalle area. It is inferred that the gold enrichment within the pyrite occurred as a result of the dissolution-reprecipitation of Py1 during metamorphic recrystallization.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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 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".