Geochronology, geochemistry, and Hf isotopic compositions of the Early Devonian Heihaibei granite in the East Kunlun Orogen, Northwest China
Bibliographic record
Abstract
The East Kunlun Orogen (EKO) is located in the western part of the Central Asian Orogenic Belt, and it records the Neoproterozoic–Early Devonian tectonic evolution involving the subduction and extinction of the Proto-Tethys Ocean. The Heihaibei granite is located in the South Kunlun belt within EKO. In this study, geochronology, geochemistry, and Hf isotope analysis of Heihaibei monzogranite and granodiorite were carried out. Their LA-ICP-MS zircon U-Pb results yielded ages of 414.1 ± 2.0 and 417.8 ± 2.0 Ma. The Heihaibei granite is peraluminous (A/CNK = 0.99–1.30), with high alkali contents (7.76–9.14 wt.%) and 10 000 Ga/Al (2.60–3.38), FeOT/MgO (27.6–49.5), and Y/Nb ratios (1.93–2.93), suggesting that the Heihaibei granite is an A2-type granite. The Heihaibei granite samples have zircon εHf(t) values ranging from −6.3 to −0.3, which suggests that the Early Devonian granite was derived from partial melting of Mesoproterozoic ( TDM2 = 1797–1415 Ma) crust. When considering data on contemporaneous granites, geochronological and geochemical data for the Heihaibei granite indicate that it was emplaced in a post-collisional extension environment following the closure of the Proto-Tethys Ocean. The Heihaibei granite was formed by extension of the southern subduction accretionary complex as part of the post-collisional setting during the closure of the Proto-Tethys Ocean.
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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 | 0.001 | 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) | 0.000 | 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".