Arc magmatic activity of Qingbaikou Period along the southeastern margin of Yangtze Block: Implications from the zircon U-Pb age and geochemical characteristics of Nb-enriched gabbro and high-Mg diorite in the Jinhua plutonic complex
Bibliographic record
Abstract
In order to probe into the Neoproterozoic magmatic activity along the southeastern margin of Yangtze Block, the authors conducted petrographic, geochemical and chronologic studies of the first-discovered Nb-enriched gabbros(NEGs) and high-Mg diorites(HMDs) in the Jinhua plutonic complex, Zhejiang Province. The NEGs show relatively high P2O5, Ti O2 and Nb values with(La/Nb)Nless than 1.3, similar to features of Archean and Palaeozoic Nb-enriched basalts. The HMDs have relatively higher Mg O content with Mg#higher than 62.5 and lower Ti O2 content, and are enriched in Cr but depleted in Sr, Y and HREE, consistent with features of Miocene high-Mg andesites of Setouchi volcanic belt in Japan and Piip-type HMAs in west Aleutian. The enrichment of LILE(e.g., Rb, Ba, K and Pb) and depletion of HFSE(e.g., Nb, Ta and Ti) with data e_Nd(t)+2.92 and I_Sr=0.70308~0.70474, probably indicate that the NEGs and the HMDs were formed by partial melting of mantle wedge peridotite with slab fluid metasomatism.The HMD yielded a weighted mean~206Pb/~238 U age of 848±10Ma(measured by LA-ICP-MS). Based on the regional geology andprevious studies, the authors hold that obvious island arc magmatic activity still existed along the southeast margin of Yangtze Block at Ca.848 Ma, and hence the Precambrian geotectonic evolution history of south China should be reconsidered.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 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".