ZONED TOURMALINE ASSOCIATED WITH CASSITERITE: IMPLICATIONS FOR FLUID EVOLUTION AND TIN MINERALIZATION IN THE SAN RAFAEL SN CU DEPOSIT, SOUTHEASTERN PERU
Bibliographic record
Abstract
The composition of tourmaline in the San Rafael Sn–Cu lode, in southeastern Peru, provides an important record of the early evolution of the hydrothermal system that produced the world’s richest tin deposit. Many forms, colors and compositions of tourmaline, ranging from dravite to schorl, are present in the deposit, but the late tourmaline that accompanied deposition of early cassiterite has an unusual dark green color, and exhibits a strong trend of enrichment in iron. Appearance of this tourmaline in the paragenesis coincided with a marked change in the vein style, reflecting an opening of the vein system, and a dramatic change in the mineralogy of vein and alteration assemblages, evident from the precipitation of other iron-rich minerals (Fe-rich chlorite and cassiterite). This abrupt change in the plumbing of the hydrothermal system was associated with the introduction of dilute, relatively oxidizing, externally derived waters of meteoric origin that mixed with hot magmatic brines carrying high concentrations of dissolved tin and iron. The resulting sudden cooling, dilution, and oxidation of the ore fluids created the conditions required for massive precipitation of cassiterite and formation of a very large, high-grade ore deposit.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".