Oligocene Kugmallit sequence in the Beaufort-Mackenzie Basin of Arctic Canada: Regional sequence stratigraphic framework, potential controls on sedimentation cycles and reservoir patterns
Bibliographic record
Abstract
A comprehensive synthesis of the Oligocene Kugmallit Sequence in the Beaufort-Mackenzie Basin of Arctic Canada has integrated data from the shelf, slope and deep basin, and linked shelf-break deltas and deep-water submarine fan systems. These have been evaluated for geological controls on sedimentation in different settings and for oil and gas resource potential. Sequence stratigraphic analysis of the Kugmallit Sequence in both onshore and offshore areas, based on regional 2D seismic grids and digital wireline logs, reveals the presence of two distinct extra-basinal fluviodeltaic axes which provided the bulk of the sediment fill in the Beaufort-Mackenzie Basin. They occur on the southwest and southeast margins of the basin and are separated by a tectonic high. A thick accumulation of the Oligocene Kugmallit Sequence indicates high sediment supply and rapid subsidence. The main sources of clastic sediments were to the south and southeast, but a local source area was the intervening tectonic high. Depocentre switching in the central part of the basin was controlled by northwesterly migrating shelf breaks, whereas in the southwest the northeastward progradation was a response to Cordilleran orogenesis to the south. Deposits on the southwestern margin of the basin have been removed by erosion. Turbidites in the north-central part of the basin were deposited during the early stage of Oligocene Kugmallit deposition and were initially limited to the growth fault zone in the south but later expanded northward. They are overlain by younger deltaic deposits. Four regional subsequences can be recognized within the Kugmallit Sequence, recording a progressive evolution of the sediment dispersal pattern. The nature of the subsequence boundaries varies across the basin. In the southwest, the sequence boundaries document extensive large scale submarine erosion, indicative of tectonic uplift, whereas in the southeast they are relatively conformable. In the deep-water sediments of the north-central part of the basin, deeply eroded boundaries of the subsequences can be recognized on seismic data. Different types of submarine fans, including the slope-submarine-fan, fault-controlled submarine fan and nearshore submarine fan, are the main depositional facies in the early stage for each subsequence, whereas in the late stage, deltaic and shelf deposits dominate. Mapping the four Kugmallit subsequences and identifying their internal facies offers a more refined approach to evaluating the oil and gas potential of Kugmallit strata.
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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 | 0.004 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".