Interplay of Ediacaran glaciation and sediment provenance revealed by detrital zircon U-Pb geochronology and Hf isotope geochemistry in the Bonavista Peninsula (Newfoundland)
Bibliographic record
Abstract
Abstract Identification of glacial influence in ancient active volcanic arc basins is challenging due to the overprinting effects of tectonism on the climatic fingerprint. The Neoproterozoic West Avalonian terrane records protracted arc volcanism within thick volcanic-sedimentary successions containing glacial diamictites of the Gaskiers glaciation (ca. 580 Ma). Such glaciogenic strata are recognized from deep- and shallow-marine settings in two basins in the Avalon zone of Newfoundland, i.e., St. John's and Bonavista Basins, offering an opportunity to disentangle changes in sediment provenance through terrane-scale glacial cycles. This study provides ~1800 single-grain detrital zircon U-Pb dates combined with zircon trace-element and Lu-Hf isotopic data from the glaciogenic Mercantile and Trinity Diamictites and underlying units (e.g., Monk Bay, Jones Pond, and Plate Cove East Members) in the Bonavista Basin. The maximum depositional ages of the studied units approach their depositional ages, suggesting very short (<1 m.y.) lag times from sediment generation to deposition and corroborating the presence of two Gaskiers diamictite horizons, separated by ~9 m.y. The proximal glaciomarine Monk Bay Member displays a narrow unimodal age distribution around ca. 580 Ma, contrasting with the diamictite units and older conglomeratic units, which capture a more widespread Tonian to Ediacaran age distribution with minor peaks at ca. 1000 Ma, 1400 Ma, 2000 Ma, and 2700 Ma. Zircon trace-element chemistry suggests a generally magmatic arc affinity, with lesser zircon exhibiting within-plate chemical affinities associated with lower degrees of melting. Hafnium isotopes from zircons in the Monk Bay facies record juvenile initial εHf of +2.6 to +12.0, whereas the diamictites and conglomeratic units exhibit a broader bimodal distribution in εHf of −4.9 to +15.2, suggesting an increase in sediment catchment during deglaciation. Finally, the Hf isotopic signatures from detrital zircons in the Bonavista Basin contrast with the coeval St. John's Basin, which contains more isotopically evolved zircons, demonstrating different sediment provenance and reduced connectivity between these two sedimentary basins.
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".