Geological interpretation of volcanism and segmentation of the <scp>M</scp>ariana back‐arc spreading center between 12.7°<scp>N</scp> and 18.3°<scp>N</scp>
Bibliographic record
Abstract
Abstract The relationships between tectonic processes, magmatism, and hydrothermal venting along ∼600 km of the slow‐spreading Mariana back‐arc between 12.7°N and 18.3°N reveal a number of similarities and differences compared to slow‐spreading mid‐ocean ridges. Analysis of the volcanic geomorphology and structure highlights the complexity of the back‐arc spreading center. Here, ridge segmentation is controlled by large‐scale basement structures that appear to predate back‐arc rifting. These structures also control the orientation of the chains of cross‐arc volcanoes that characterize this region. Segment‐scale faulting is oriented perpendicular to the spreading direction, allowing precise spreading directions to be determined. Four morphologically distinct segment types are identified: dominantly magmatic segments (Type I); magmatic segments currently undergoing tectonic extension (Type II); dominantly tectonic segments (Type III); and tectonic segments currently undergoing magmatic extension (Type IV). Variations in axial morphology (including eruption styles, neovolcanic eruption volumes, and faulting) reflect magma supply, which is locally enhanced by cross‐arc volcanism associated with N‐S compression along the 16.5°N and 17.0°N segments. In contrast, cross‐arc seismicity is associated with N‐S extension and increased faulting along the 14.5°N segment, with structures that are interpreted to be oceanic core complexes—the first with high‐resolution bathymetry described in an active back‐arc basin. Hydrothermal venting associated with recent magmatism has been discovered along all segment types.
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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) | 0.001 | 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 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".