Fault reactivation and structural control on sedimentation along the Laurentian passive Margin: The Cambrian to Ordovician Cow Head Group, Humber zone, Western Newfoundland
Bibliographic record
Abstract
Sedimentologic and provenance analyses were conducted on the upper Cambrian and Lower Ordovician Cow Head Group in western Newfoundland, Canada, to understand the structural control on sedimentation of these passive Laurentian margin strata. Four facies associations were identified, corresponding to submarine slope sub-environments. Facies association 1 (FA1) is characterized by amalgamated sheet-like architectural elements composed of debris and hyperconcentrated transitional to concentrated flow strata, comprising sections through the Miaolingian series and across the Cambro-Ordovician boundary. FA1 occurs both below and above Furongian FA2 and its coeval distal FA3, and beneath the Lower Ordovician FA4. High-energy sedimentary processes such as reflected turbidity currents and/or tsunami-related oscillatory currents are recorded in Furongian stratigraphy of FA2 by HCS-like stratification, and these strata are capped by boulder mega-conglomerates at the Cambrian-Ordovician boundary recording shortdistance rock fall processes related to basin margin collapse (FA1). These strata are overlain by facies recording calmer depositional conditions in the Early Ordovician, characterized by low-concentration turbidity currents (FA3). Together, these facies associations record the transition from a platform margin fault scarp basin (FA1) to a confined submarine basin, including confined slope (FA2) and lower slope to basin floor (FA3) settings, succeeded by basin margin collapse during the Cambrian-Ordovician transition (FA1) and an Early Ordovician passive toe of slope sedimentation (FA4). Paleocurrent measurements indicate a southward-facing submarine paleoslope. U-Pb geochronology and Lu-Hf isotopic analysis of detrital zircon suggest sediment recycling of earlier deposited Paleozoic shelf units and erosion down to Ediacaran igneous rift-related rocks on the margin, implying tectonic uplift and transverse fault reactivation along the Laurentian margin. The regional significance of this late Cambrian to Early Ordovician (495 to 480 Ma) sedimentary succession highlights the structural control on the Laurentian passive margin, and is consistent with its existing rift-architecture models and links to the geodynamic evolution of the Taconic Seaway.
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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 | 0.001 | 0.001 |
| 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) | 0.001 | 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".