Patterns of distal alteration zonation around Antamina Cu-Zn skarn and Uchucchacua Ag-base metal vein deposits, Peru : mineralogical, chemical and isotopic evidence for fluid composition, and infiltration, and implications for mineral exploration
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Bibliographic record
Abstract
Intrusion-related, carbonate rock–hosted replacement deposits are an important source of global base metal production that includes: Cu-Zn skarn, Zn-Pb-Ag carbonate replacement and Ag-base metal deposits. These deposits are located in multiple geological settings and are commonly associated with low-grade Cu-Mo calc-alkaline porphyry districts. Visible alteration halos to these deposits range from ten to hundreds of metres around high temperature skarn deposits, being small to imperceptible around the distal relatively low temperature members of this clan. Patterns of visible and cryptic alteration are described and constrained in this study particularly around paleo-fluid flow zones at different distances and elevations from the ore centre. This was done in order to identify the large-scale zonation, mechanisms, and effects of fluid infiltration especially into the distal portions of these deposits. The main alteration tracers employed included mineralogy, major and trace element geochemistry, oxygen and carbon isotopes, and the fluorescent signature of calcite veins associated with the fluids conduits. Two areas were selected for this study: the large Cu-Zn Antamina skarn and the Ag-base metal Uchucchacua vein deposits in the Peruvian Central Andes as these deposits represent the end-members of the polymetallic carbonate rock-hosted deposits and hence, provide an excellent opportunity to examine the margins and upper sections of these hydrothermal systems. Geochronological analyses of intrusive dikes were used to establish the magmatic and hydrothermal evolution associated with mineralization, as well as the genetic linkage between proximal and distal portions of the mineralizing system at Antamina. Oxygen, carbon and strontium isotope data of vein minerals is also used to constrain the temperature of the fluids proximal and distal to the magmatic centre. Chemical data of fluorescent and non-fluorescent veins were used to determine the main activators of fluorescence and to constrain its relationship with mineralizing fluids. In summary, results of this research identify a large-scale zonation of visible and cryptic alteration around paleo-fluid flow zones demonstrating the linkage between Ag-base metal veins, replacement and skarn deposits. Anomalous halos determined throughout Antamina and Uchucchacua deposits may contribute to the development of a more systematic exploration methodology for these types of deposits.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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 it