The Timing of Magmatism and Ore Formation in the El Abra Porphyry Copper Deposit, Northern Chile: Implications for Long-Lived Multiple-Event Magmatic-Hydrothermal Porphyry Systems
Bibliographic record
Abstract
Zircon LA-ICP-MS and CA-TIMS and molybdenite Re-Os geochronology for the El Abra porphyry copper deposit (Chile) document a ~8.6 Ma protracted magmatic-hydrothermal history. Initial magmatic events occurred at ~45 Ma, and continued to ~36 Ma. An ~1.8 m.y. magmatic lull is recorded in the early stages of magmatism, which is characterized by equigranular rocks from the Pajonal suite. Magmatism from ~41 to ~36 Ma, corresponding to the El Abra Granodiorite Complex, is more recurrent, ending in a ~1.4 m.y. period of porphyritic intrusions, which are coeval with Cu-Mo mineralization. Late porphyritic units reveal subtle zircon inheritance likely associated with early magmatic pulses. The young stages of magmatism indicate system rejuvenation based on plagioclase phenocryst compositions, suggesting that the porphyry system is ultimately linked to a less evolved magma. Although there are multiple porphyry and veining events, molybdenite Re-Os ages define a focused mineralization episode from 36.34 to 36.18 Ma. Molybdenite Re-Os ages from nearby related prospects belonging to the El Abra cluster expand the mineralization period in the district up to ~1.0 m.y., suggesting a multistage, long-lived hydrothermal system. Integration of the molybdenite Re-Os dates and those from previous works at the El Abra and Toki clusters, accompanied by available tectonic reconstruction along the Domeyko fault system suggest the development, by late Eocene times, of a single, large (~30 km across) porphyry copper cluster, which was subsequently separated by an offset of ~35 km along the West fault.
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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) | 0.000 | 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 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".