Petrology and Mineralogy of Lower Cretaceous sedimentary rocks, Dauntless D-35 well, Scotian Shelf
Bibliographic record
Abstract
The sedimentary petrography of the Lower Cretaceous (2160 - 3600 m) in the Dauntless D-35 well has been studied from cuttings samples and one short conventional core. The 3.5 m long conventional core was logged sedimentologically and sampled for petrographic thin sections. 37 cuttings samples were studied in detail and a "heavy mineral" fraction was separated. Detrital minerals diagnostic of provenance were analysed by electron microprobe and their chemical composition compared with elsewhere in the Scotian basin and with bedrock in the hinterland. Diagenetic minerals were characterized by scanning electron microscopy of rock chips, backscattered electron images of thin sections, and electron microprobe analysis. The conventional core from the upper Missisauga Formation consists of medium-coarse grained sandstone beds deposited as river-mouth turbidites. These beds are cut by liquefied sandstone sills. Sandstones in the conventional core are largely silica cemented, but in places silica overgrowths were inhibited by the presence of chlorite rims. Kaolinite was an earlier pore-filling cement. Halite is interpreted as a later diagenetic cement. Lithological characterization of the cuttings samples shows substantial down-hole contamination. The "heavy mineral" fraction is dominated by carbonate cemented chips and few diagnostic detrital minerals or lithic clasts were found. The cuttings samples contain sideritecemented mudstone and siderite or calcite - Fe-calcite cemented muddy sandstone, both probably formed during sea-floor diagenesis. As in the Sable sub-basin, siderite with high Ca and Mg is most abundant in the Logan Canyon Formation. Late carbonate cements are rare. In both cuttings and conventional core, K-feldspar makes up 3 - 5 % of the framework grains. Almandine garnet is sourced principally from (meta)mafic igneous rocks. All analysed tourmaline and most analysed biotite is of metasedimentary provenance. Chromite and chrome spinel indicates an ophiolitic source and is distinctive in the presence of ferrian chromite and the absence of boninitic chromite. Identifiable lithic clasts are principally of granite and volcanic rocks, the latter perhaps from Cretaceous volcanic rocks in Orpheus graben. The detrital assemblage is similar to that in the Peskowesk A-99 well, but differs in important respects from wells in the Sable sub-basin, notably the abundance of K-feldspar and different assemblages of garnet and chromite.
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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 | 0.001 |
| 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) | 0.001 | 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".