The stratigraphical context of the Ediacaran Biota of eastern Newfoundland
Bibliographic record
Abstract
Detailed geological mapping and improved understanding of the geological evolution of the siliciclastic late Ediacaran rocks of the Mistaken Point Ecological Reserve (MPER) and the Catalina Dome, both of Newfoundland, provide a new framework for improved lithostratigraphic subdivision of the successions. The lithostratigraphic correlation of the Catalina Dome with the succession at MPER is found to be incorrect, prompting the erection of the Trinity Bay North Group to classify the rocks of the Catalina Dome. U-Pb (zircon) ages from the successions provide essential temporal constraints on the rise and fall of the Ediacara biota, and show that the Catalina Dome sections are up to 5 Myr older than previously thought. Both the MPER and Catalina Dome successions show an early fossil assemblage characterised by the presence of Trepassia and Vinlandia ; a taxonomic radiation ∼575 Ma; the emergence of evidence for animals ∼565 Ma; and the sudden disappearance of most forms within post-565 Ma slumped slope deposits. These points provide the basis of discussion around the potential for a biostratigraphy for the Ediacaran of Avalonia, and support the 'Ediacaran Explosion' hypothesis. Previous research using sedimentary strucutres and geochemical proxies to assign a nonmarine deposition environment to the MPER and Catalina Dome sections is found to be flawed and without merit. There is no evidence for shallow marine or sub-aerial depositional environments. All known Avalonian rangeomorphs are found in deep-marine facies. The environmental controls on the stratigraphic distribution of taxa remain poorly constrained. Analysis of tuffites within MPER suggests they were deposited by ashy turbidity currents, rather than as ash-falls. This prompts caution when using these tuffites for geochronological analysis, and requires the re-evaluation of the traditional taphonomic model for rangeomorph fossilisation. 'Post-fossilisation processes' are shown to bias fossil census studies, most notably through differing mechanisms of tuffite weathering and erosion. The impacts on palaeoecological studies, and geoconservation efforts are considered. The geoconservation legislative frameworks for Newfoundland and England are compared and contrasted, and recommendations made.
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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 | 0.002 |
| 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".