Stenian–Tonian arc magmatism in west–central Madagascar: the genesis of the Dabolava Suite
Bibliographic record
Abstract
Madagascar is a complex, composite geological terrane that occupies an important location in Late Proterozoic plate reconstructions. The recognition in one of the Madagascan terranes of a Stenian to Tonian-aged arc magmatic suite (the Dabolava Suite) demonstrates that its host terrane resided at a plate boundary from c. 1080 to 980 Ma. Gabbroic and granitoid intrusions of the Dabolava Suite are recognized only in the Ikalamavony Domain in west–central Madagascar. The oxygen isotopic compositions of zircon indicate that the parental magmas involved crustal contributions that were fractionated by a hydrological cycle, whereas hafnium isotopic compositions reflect near depleted-mantle signatures with only minor deflection to more crustal values. Together, these trends suggest mantle derivation of parental magmas coupled with upper-crustal assimilation of Stenian-aged pre-existing plutonic and volcanic rocks. These magmatic rocks, together with the coeval sedimentary rocks of the Ikalamavony Group, are taken to represent a subduction-related magmatic arc that formed in an oceanic-arc tectonic setting in the Mozambique Ocean outboard of the Archaean to early Palaeoproterozoic shield of Madagascar. The arc accreted to the older craton before the initiation of the Imorona–Itsindro Suite magmatism at c. 850 Ma that intruded both domains. Supplementary material: A complete description of the analytical methods and supplementary data are available at https://doi.org/10.6084/m9.figshare.c.3823717
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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) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".