Garnet granulites of Sutam River middle current sutam river (Aldan Shield) as possible indicators of metamorhosed and tectonically displaced Post-Hadean weathering crust
Bibliographic record
Abstract
The article discusses the problem of the nature of high-alumina garnet granulites from Sutam River (Aldan Shield). The studies revealed that the majority of detrital grains have U-Pb age of up to 1.92 Ga; however the zircon grain of 3.94 Ga has been for the first time discovered in Russia. This age is estimated as the upper limit of the Hadean eon. The goals of the present studies were to reveal the petrogenesis of garnet granulites and to find out the origin of the Hadean zircon in these garnet granulites and the mechanisms of injection diapirism of garnet granulite body to the upper horizons of the crust. The comparison of garnet granulites and middle crust showed that the granulites are enriched in the whole spectrum of rare earth elements (except of Eu) as well as Al 2 O 3 , U, Th and are depleted in Na, Ca и Sr (the most mobile elements). This in combination with other geochemical indicators suggested the granulite protolith as an upper part of the allite zone of middle crust weathering, formed in arid climate. The Hadean zircon grain is regarded as having been captured from the granites of middle crust. The diapirism of garnet granulites (with the captured Hadean zircon) proceeded during the Paleoproterozoic thermotectogenesis of the Aldan shield which were accompanied by the horizontal propagation of deep-seated granite-anorthosite tectonic flows from the plume’s center to its periphery. During the movement of these flows the fragments of the lower and middle crust were shifted both laterally and vertically. When they moved vertically they were discretely intruded in the upper granite-gneiss crust (1.83-1.82 Ga) under high pressure. The 3.94 Ga zircon is comparable with the Hadean zircons from Acasta orthogneiss (Canadian shield, 4.03-3.94 Ga, SHRIMP and ID-TIMS).
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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 | 0.002 | 0.001 |
| 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) | 0.001 | 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".