Cretaceous felsic volcanism in New Zealand and Lord Howe Rise (Zealandia) as a precursor to final Gondwana break-up
Bibliographic record
Abstract
Abstract We report new, highly precise, U–Pb and Ar/Ar ages for seven Cretaceous rhyolites, tuffs and granites from across Zealandia spanning a 30 Ma period from arc magmatism to continental break-up. Combined with previously published data, these reveal a strong episodicity in Cretaceous silicic magmatism outside the Median Batholith. 112 Ma tuffs are known only from the Eastern Province in association with a Cretaceous normal fault system. Both 101 and 97 Ma groups of rhyolites and tuffs occur across the entire width and half the length of Zealandia from near the palaeotrench to the continental interior, indicating widespread and effectively instantaneous extension. We attribute an increase in A-type character with time (112–101–97–88–82 Ma) to the progressive thinning of the Zealandia continental crust whereby, with time, there is less opportunity for crustal contamination. Extension directions associated with 101, 97 and 82 Ma magmatism and associated core complex exhumation across Zealandia are all oriented c. 30° oblique to the margin. These observations suggest Zealandia rifting was controlled by either >83 Ma capture of Zealandia by the Pacific Plate and/or <83 Ma Zealandia–West Antarctica spreading, rather than by laterally migrating triple junctions, slab windows or plume heads.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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 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".