Sediment provenance and diagenesis, Lower Cretaceous of the Alma K-85 well, Scotian Shelf
Bibliographic record
Abstract
Eight conventional cores from the Alma K-85 well have been logged and sampled. They represent the Albian Cree Member of the Logan Canyon Formation and the predominantly Barremian Upper Member of the Missisauga Formation. Compared with other wells in the southwestern Sable sub-basin, prodeltaic turbidites are rare and sediments comprise principally shoreface sandstones and open shelf mudstones. The Upper Missisauga interval accumulated on a prodelta slope and almost all sandstones are part of slide blocks 10-15 m thick. Detrital petrology is strikingly different from that of the Abenaki sub-basin, as represented by the Peskowesk A-99 well. The sandstones at Alma are principally quartz arenites, in contrast to sublitharenites at Peskowesk. At Alma, the predominant feldspar is plagioclase and lithic clasts from metamorphic and sedimentary sources are more abundant than at Peskowesk, which appears to have a predominantly felsic igneous source with abundant Kfeldspar. A substantial component of the sediment at Alma has a polycyclic source, probably from Carboniferous or Lower Paleozoic sandstones, resulting in the concentration of resistant heavy minerals such as chromite/spinel and zircon, and perhaps tourmaline and garnet. Nevertheless, the dominant chemical types of garnet, tourmaline, detrital chlorite and igneous muscovite are all consistent with sources in the Meguma terrane. Spinel/chromite, tourmaline and plagioclase all show little change in abundance with depth, suggesting that the source of sediment remained approximately the same throughout the sampled interval. In contrast, garnet appears to become diagenetically unstable at depth and less K-feldspar appears to have been supplied. The paragenetic sequence of diagenetic minerals is similar to that found elsewhere in the southwestern Sable sub-basin, with some early kaolinite and important early and late Fe-calcite cements. However, Fe-silicate minerals resulting from suboxic reduction of Fe, characteristic of brackish water and low organic carbon, are very rare, and even siderite is uncommon. These observations reflect the dominance of fully marine (shoreface and open shelf) lithofacies, and accounts for the absence of chlorite rims on quartz grains. The lack of late ankerite cement may also be related to the relative paucity of siderite.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 teacher head, 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".