Geochronological and geochemical data of paragneiss and amphibolite from the Chencai Group in South China: Implications for petrogenesis and tectonic significance
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Bibliographic record
Abstract
We carried out an integrated study of zircon U–Pb geochronology, Hf isotopes and geochemistry on the paragneisses and amphibolites from the Chencai area, South China. The detrital zircon ages of four paragneisses range from 2974 to 501 Ma with the main peak at ca. 820 Ma. The detrital materials with Neoproterozoic age may derive from the Jiangnan Orogen and those of Palaeo–Mesoproterozoic age may come from the Wuyi terrane. The youngest age indicates that the protoliths of the paragneisses were formed after ca. 501 Ma. The ε Hf ( t ) values (−20.6 to +20.9) of the detrital zircons suggest that the detrital materials of the protoliths are composed of old crustal and juvenile materials. The geochemical characteristics suggest that the protoliths of the paragneisses are greywackes, which formed in an active continental margin or continental island arc environment. The metamorphic ages of the three amphibolites are 428 ± 4, 430 ± 4, and 438 ± 3 Ma. The protoliths of the amphibolites are tholeiites, which can be divided into two groups. Group 1 is characterized by low ∑REE contents and (La/Yb) N ratios showing left‐inclined REE patterns and Nb, Ta depletion which resembles N‐MORB. Group 2 has higher ∑REE contents and (La/Yb) N ratios, with Eu negative anomalies showing affinity to E‐MORB. The data show that the Chencai Group is composed of oceanic crust remnants and continental crust materials, indicating it should be a subduction accretionary complex rather than a metasedimentary sequence and thus it cannot be regarded as the Precambrian basement of the Cathaysia Block.
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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 | 0.001 |
| 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 | 0.001 |
| 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 it