Middle to Late Permian Sedimentation in the Sverdrup Basin, Canadian Arctic: A 40-Year Old Stratigraphic Problem Resolved
Bibliographic record
Abstract
Summary Contrary to a long-held belief, Upper Permian strata are present in the Sverdrup Basin of Arctic Canada, and a nearly continuous conformable record with the overlying Blind Fiord Formation occurs in the basin central area. These strata are dominated by spiculitic chert that forms an entirely separate unconformitybounded transgressive-regressive sequence. The Wuchiapingian Sequence is one of four sequences that encompass the Middle Permian to Lower Triassic interval. Two new stratigraphic units have been formally erected for the first time to better account for Upper Permian strata in the Sverdrup Basin. The Lindstrom Formation is a unit of white to pale grey spiculitic chert that represents sedimentation on a shallow, open marine, wave- and storm-dominated ramp. The Black Stripe Formation, which is in part correlative with the Lindstrom Formation, comprises black to dark grey spiculitic chert associated with siliceous shale and siltstone of slope to basinal origin. The upper part of the Black Stripe Formation comprises a deepeningupward succession of black cherty siltstone and siliceous shale that recorded Changhsingian sedimentation. The basal Blind Fiord contact which coincides with the Latest Permian Extinction event in the Sverdrup Basin is marked by an unusual abundance of pyrite, a hallmark of the extinction horizon around the world. A seemingly-rapid, yet progressive carbon isotopic shift across the Black Stripe-Blind Fiord contact in distal settings suggests a continuous stratigraphic record, even though a hiatus associated with maximum flooding and condensation does exist. The Late Permian age of the Lindstrom and Black Stripe formations is substantiated by conodont biostratigraphy and carbon isotope chemostratigraphy. Late Changhsingian conodonts were recovered from the base of the Blind Fiord Formation, while Hindeodus parvus, the species that marks the base of the Triassic at the GSSP in China, and associated conodont assemblages, occurs a few tens of metres above the base of the Blind Fiord Formation. Black shale in the Lindstrom and correlative Black Stripe Formation may have a genuine source potential as shown by high TOC values and preliminary RockEval analysis.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.005 | 0.004 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| 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".