Mesozoic overprinting of the Precambrian Wuhe Complex, southeastern margin of the North China Craton: Insights from geochronology and geochemistry
Bibliographic record
Abstract
The formation of Meso-Neoarchean metagranitoids from the Wuhe complex (WC), southeastern margin of the North China Craton (NCC) and the nature of Mesozoic tectonothermal overprinting are unclear. It is the importance of understanding Phanerozoic overprinting in Archean complexes for obtaining a complete understanding of the evolution of the NCC. The WC is composed of ∼2.8 Ga granitic gneiss , ∼2.7 TTG gneiss , 2.1 Ga and 800–700 Ma granitic gneiss, all of which are intruded by 160 Ma granite. The Meso-Neoarchean rocks were affected by multiple tectono-magmatic-metamorphic thermal events at ca. 2.7 Ga, 1.85–1.80 Ga, 220 Ma and 160 Ma. Metamorphic overprinting at ∼220 Ma, anatexis at ∼160 Ma, and the presence of ∼750 Ma and ∼220 Ma inherited zircons in a 156 Ma granite strongly suggest that the Yangtze Craton (YC) were underthrust beneath the southeastern margin of the NCC by the late Triassic during continental subduction associated with the Dabie–Sulu orogeny . Lithological, geochemical, and isotopic evidence indicate that the ∼2.8 Ga granitic gneiss of the WC were derived from partial melting of previous continental crust ; this provides a new petrogenetic interpretation of Mesoarchean (∼2.8 Ga) granitic gneiss in the region. The ∼2.7 Ga TTG gneisses were derived from partial melting of juvenile basaltic crust with a contribution of ancient crustal material. The geochemical data, in conjunction with similar ages of inherited zircon (∼2.7 Ga) and zircon from Neoarchean TTG gneiss (∼2.7 Ga), indicate that the ∼2.1 Ga granitic gneisses were derived from partial melting of the Neoarchean (∼2.7 Ga) TTG gneiss. In addition, newly-identified Neoproterozoic (800–700 Ma) granitic gneiss with Triassic metamorphic ages, combined with the Neoproterozoic and Triassic inherited zircons in the Jurassic granites, further suggest that the YC continental crust was subducted beneath the NCC in the Triassic and acted as the source region for the Jurassic granites at ∼156 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 | 0.000 | 0.000 |
| 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 | 0.000 |
| 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 teacher head, 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".