Simple parasequences in a medial shelf setting: Albian Sikanni Formation, Northwest Territories, Canada
Bibliographic record
Abstract
We document medial shelf parasequences in the Upper Albian Sikanni Formation in the Liard Basin, Northwest Territories, Canada, deposited during a greenhouse climate in the Western Interior Cretaceous Seaway. It is characterised as a fine-grained glauconitic sandstone with argillaceous shales, ranging approximately 100 to 300 metres in thickness. We measured 111 metres of section, passing from sandier to more distal shale facies towards the contact with the conformably overlying Sully shale, indicating an overall deepening. The sandier section shows well-organised upward coarsening facies successions, transitioning from wave to hummocky cross stratified sandstones to pervasively bioturbated sandstones, dominated by Zoophycos to distal Cruziana ichnofacies, interpreted as a medial shelf environment. There are at least 8 well-expressed parasequences in the sandier lower part of the section, transitioning into more uniform shalier units near the contact of the Sully Formation. The sandier parasequences are sharply bounded by shales forming well-expressed ‘simple parasequences’. Simple parasequences are defined as upward-coarsening facies successions lacking evidence of key bounding surfaces indicating bypass or subaerial exposure, such as lag deposits, roots, or transgressive erosion. These are distinguished from ‘complex parasequences’, commonly containing these features. The changing environment of the more uniform muddier facies can be distinguished using increases and decreases in bioturbation, corresponding to lower and higher sedimentation rates, respectively. The Sikanni units lack evidence of subaerial exposure, indicating that it is unlikely the parasequences shallowed up to the shoreline. Nevertheless, these cycles are well-expressed, suggesting that simple parasequences can be identified in medial shelf environments. Additionally, a guiding framework based on Dene (First Nations) principles was developed as a basis for this project. The phases on the framework are: (1) Decolonisation of the Self, (2) Building Relationships and Community Consultation, (3) Community Entry and Data Collection, (4) Data Analysis, and (5) Knowledge Translation and Dissemination. A special thanks to Acho Dene Koe First Nation in the community of Acho Dene Koe, Northwest Territories, for graciously welcoming us onto their lands, into their community, and allowing us to share the geologic stories of the rocks they have coexisted with since time immemorial.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 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".