Petrogenesis of Early Neogene Magmatism in the Northern Puna; Implications for Magma Genesis and Crustal Processes in the Central Andean Plateau
Bibliographic record
Abstract
of UOLM-2 and MM group rocks.Assuming the same end-New compositional data and petrogenetic models are presented for member compositions, the modelling suggests genesis of the MM pre-Upper Miocene volcanism in the northern Puna of Argentina magmas at higher pressure than the UOLM-2 centres ([10 kbar (22°S-24°S).Two phases of volcanism produced small dome vs 7 kbar), which may reflect the influence of crustal thickening in complexes of mainly silicic andesite to low-SiO 2 rhyolite.The the plateau region by the mid-Miocene.The felsic dome complexes Upper Oligocene-Lower Miocene phase (UOLM, 20-17 Ma), of this study are compositionally similar to the large-volume, calderaproduced two distinct groups of rocks.The UOLM-1 group is sourced felsic ignimbrites that dominated volcanism in the region metaluminous and mainly andesitic, with isotopic compositions like from 10 to 2 Ma and our results suggest that there is no fundamental those of the recent arc ( 87 Sr/ 86 Sr T >0•706; Nd T -3).The difference in magma genesis between them.The differences in the UOLM-2 group is more silicic and peraluminous, and has isotopic volumes and the mode of eruption reflect changes in the stress and compositions indicating a substantial crustal contribution ( 87 Sr/ thermal regime with time.86 Sr T >0•713; Nd T -8).The Mid-Miocene phase (MM: 15-12 Ma) produced rocks similar in composition to those of the UOLM-2 group ( 87 Sr/ 86 Sr T >0•710; Nd T -7) but with higher incompatible element contents.Ratios of Ba/Nb and Zr/ KEY WORDS: Cenozoic volcanism; Central Andes-Puna Plateau; crustal Nb in the UOLM group rocks are uniform and similar to those of assimilation; dacitic magmas; geochemical modelling the current arc, whereas the ratios in MM centres show a mixed arc and back-arc affinity.This suggests that the westward shift in the arc began in the northern Puna in the mid-Miocene.Neither the exposed Palaeozoic felsic basement nor the lower-crustal gran-
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".