GEOQUÏMICA E GEOCRONOLOGIA DE ROCHAS GNAÍSSICAS PALEOPROTEROZÓI- CAS DO COMPLEXO PARAÍBA DO SUL (UNIDADE QUIRINO), REGIÃO DE BARRA MANSA, RIO DE JANEIRO, BRASIL
Bibliographic record
Abstract
This paper presents and discusses new geochemical data from orthogneisses rocks of Paraiba do Sul Complex (PSC) from the NW of the Rio de Janeiro State, denominated Quirino Unit. U-Pb geochronological data (carried out on GEOTOP-UQAM, Canada), displayed in Valladares (1996) and Machado et al. (1996), are also discuss. This Unit, as well the Metasedimentary Unit of PSC and intrusive brazilian granitoids, comprise the Paraiba do Sul Tectonic Domain (PSTD) or Upper Tectonic Domain, at the central segment of the Ribeira belt. The Quirino Unit occurs as extensive bodies of homogeneous gneisses of upper amphibolite facies metamorphism, with hornblende and or biotite comprising approximately 50% of the studied area and ca. 70% of the PSTD. This unit yields U-Pb zircon ages of 2185±3 Ma and 2169±3 Ma, temporally related to the Transamazonian event. Minimum ages of 2846 Ma and 2981 Ma (zircon U-Pb data) reveal the pre-existence of Archean crust as Pb source of part of the investigated gneisses. Geochemical studies of orthogneisses Quirino discriminate two calc-alkaline suites: one of medium to high-K and other of high-K, with enrichment in LILE. The chemical characteristics and the ages U-Pb allow to perform a tectonic correlation of the Quirino Unit with arc magmatic calc-alkaline granitoids, which were generated during the Transamazonian orogeny (2.2 - 1.9 Ga). Ages between 605-503 Ma (zircon and sphene U-Pb data) indicate reworking of Quirino Unit during Brazilian Orogeny (ca. 700-450 Ma).
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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 | 0.005 | 0.004 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.004 | 0.002 |
| Scholarly communication | 0.006 | 0.001 |
| Open science | 0.009 | 0.003 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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; both teacher heads agree on what is shown here.
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".