Significance of New Ediacaran Fossils and U‐Pb Zircon Ages from the Albemarle Group, Carolina Terrane of North Carolina
Bibliographic record
Abstract
The Albemarle Group is one of the major defining stratigraphic units of the Carolina terrane, the best‐known division of the southern Appalachian peri‐Gondwanan block of Carolinia. As such, the group is a significant factor in the correlation of Carolinia with other peri‐Gondwanan blocks both in the Appalachians and globally. The traditionally held Ediacaran age of the group has been in question for more than a decade because of a report of Late Cambrian and younger fossils from two quarries in the group. The fossil report led to a major revision of the stratigraphy and structural reinterpretation of the Carolina terrane. Our recent studies have focused on the stratigraphy, paleontology, and geochronology of the Cid Formation in the vicinity of one of the reported Paleozoic fossil locales. Contrary to the structural reinterpretation of the Albemarle Group, Cid mudstone is shown to be in conformable and gradational contact with Flat Swamp felsic volcanics of the Cid Formation; we have obtained a precise U‐Pb zircon age of $$547\pm 2$$ Ma for the volcanics at a nearby locality. We also recovered the Ediacaran fossil Aspidella from the Cid mudstone. In conjunction with the new stratigraphic and geochronological data, the new fossil find leads us to consider the Cid Formation to be Ediacaran. These new data support a mainly Neoproterozoic age for the lower half of the Albemarle Group, indicating that major stratigraphic and structural revisions of the Carolina terrane based on the supposed Paleozoic fossils are unwarranted. Confirmation of the stratigraphy of the Albemarle Group has a bearing on the correlation of Carolinia with other peri‐Gondwanan crustal blocks in the Appalachian Orogen.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".