THE MANGANESE DEPOSITS OF THE PAMPEAN RANGES, ARGENTINA
Bibliographic record
Abstract
The example of manganese mineralization studied in this paper makes up the major concentration of this element in Argentina. It comprises an area of 70 by 30 km in the eastern Sierras Pampeanas, located in Cordoba and Santiago del Estero provinces. It is quite unusual since it is hosted in granodioritic and rhyodacitic rocks. Geochemical, petrological and structural analyses demonstrate that these rocks are unrelated to the mineralization process. The geometry and distribution of the veins are controlled by a dextral shear system related to north–south lineaments. Textural and structural analyses of the veins indicate four different stages of mineralization. Ore minerals precipitated during the first three, whereas the gangue was mainly formed during the last stage. X-ray diffraction and electron-microprobe studies show that Mn 4+ oxides (hollandite, pyrolusite, ramsdellite, romanechite and cryptomelane) associated with Fe 3+ oxides (goethite and hematite) are the main ore minerals. Calcite, opal, barite, and lesser amounts of fluorite, quartz and “chalcedony” are the most common gangue minerals. Fluid-inclusion studies show that this mineralization was associated with aqueous solutions of low salinity and a temperature of about 125°C. Isotopic analyses based on several samples of calcite (δ 13 C, δ 18 O) and barite (δ 34 S, δ 18 O) have demonstrated the dominance of meteoric waters in the hydrothermal fluids. Finally, the chemical composition of manganese oxides supports the hypothesis of an epithermal system developed in continental environments.
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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) | 0.001 | 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".