Bibliographic record
Abstract
The volcanoes of the northern lzu - south-cental Honshu and northeastem Honshu arcs, Japan, occur in a region where vmiables such as age, conposition, and nature ofthe sediment cover oftle subducting plate are relatively uniform. In this study, v/e attempt to isolate some ofthe variables associated with suprasubduction zone (SSZ) magma genesis, in order to provide insight into ttre nature of sources and petrogenetic processes. The chemical compositions of selected parental and evolved magmas in fifteeu Plio-Pleistocene centers along the strike ofthe volcanic front allow us to assess tle significance of over-riding lithospheric input for SSZ magmatism. These volcanoes are distributed across a number of major terrane boundaries, including the lithosphere-penetrating Tanakura Tectonic Line. Conpositions range from basalt to rhyolite, with a preponderance of basaltic andesite and andesite; an exception is basalt-dominated Fuji. Most basalts are signiffcmfly fractionate4 with low MgO ( 3) and Dy/Yb, indicative of gamet involvement in their gercsis. The Nd and Sr isotope ratios also indicate regional variations in chemical composition of the source(s) (ong-term depleted to enriched). Pb isotopic data are distinctive in northern Honshu, with elevated 48Pb/2I/.Pb afi,NTPbPePb at specific 2n6Pb2oaPb (south versas north of the Tanakura Tectonic Line), are collectively elevated above the Northem Hemisphere Reference Line (and lzu-Mariana arcs), appear similax to portions of the Philippines and Tertiary basalts of eastern Asia and probably reflect an Asian lithospheric heritage. The combined trace-element and isotope geochemistry of parental basalts distinguish different domains within the Izu-Bonin, central and northeastern Honshu arcs. The ultimate cause of these is most likely multicomponent, and some crustal assimilation is higbly probable. However, tlese domains may in some paxt represent nagma interaction with a subcontinental lithosphere dominated by Indian-Ocean-type or alt€matively, derivation from an Indian-Ocean-type asthenosphere. The correlation of some magma compositional characteristics with nature of the basement terrane shows that the lithosphere plays a subtle but significant role in determining parental island-arc basalt chaxacteristics. The longevity and character ofthe continental lithosphere in Asian margin arc systems, and its interaction with asthenosphere-derived melts, is a1 imFcntant process in island-arc basalt genesis.
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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) | 1.000 | 1.000 |
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; both teacher heads agree on what is shown here.
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".