Petrogenesis of Mafic-Ultramafic Intrusions in the Southern Goiás Magmatic Arc, Central Brazil
Bibliographic record
Abstract
The Americano do Brasil and Mangabal Complexes belong to a cluster of Neoproterozoic mafic-ultramafic intrusions in the southern Goiás Magmatic Arc in Brazil that lies within the Brasília Belt, a complex, long-lived Neoproterozoic Orogen that formed during the amalgamation of the São Francisco/Congo, Amazonian, and Paranapanema Cratons in western Gondwana.Although deformed and partially recrystallized by a regional metamorphic overprint, the rocks of both complexes still preserve igneous textures.The rocks in both complexes show cumulate textures that range from adcumulate to orthocumulate.Petrography, geochemistry, geochronology, and petrological modeling were carried out to constrain the petrogenesis of the complexes.Modeling indicates that the parental magma for the Americano do Brasil Complex had an OIB-like Fe-rich picrite composition, while the parental magma of the Mangabal Complex could have been a tholeiitic basalt.Considering the temporal and spatial correlations, decompression melting of upwelling asthenosphere triggered by rollback subduction and/or influence of a mantle plume are plausible mechanisms to explain the petrogenesis of these mafic-ultramafic intrusions in the vicinities of the eastern Arenópolis arc and westernmost Anápolis-Itauçu belt.The complexes have experienced a protracted metamorphic evolution with peaks indicating amphibolite facies.The rock from both complexes shows late-stage alteration associated with metasomatism by CO2-Ca-S-rich fluids.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| 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".