Upper Jurassic - Lower Cretaceous lithofacies, detrital petrology and diagenesis of the Louisbourg J-47 well, Scotian Shelf
Bibliographic record
Abstract
The sedimentary petrography of the Lower Cretaceous and Upper Jurassic in the Louisbourg J-47 well has been studied from five conventional cores. The core was logged sedimentologically and sampled for petrographic thin sections. 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 backscattered electron images of thin sections, and electron microprobe analysis. Conventional core shows three facies associations. 1) In the Verrill Canyon Formation, thick blocky mass-transport deposits predominate. (2) In the Upper MicMac Formation, the cored succession is similar to coeval rocks assigned to the Lower Missisauga Formation at Venture and Thebaud. Delta-front turbidites pass up into tidal channel sands in parasequences that are characteristic of shelf-margin deltas with adequate accommodation. (3) In the Middle Missisauga Formation, a delta-top succession is present in which tidal flat and thin shelf sediments predominate. Some 60-70% of the detrital quartz is interpreted to be derived from granitoid rocks. Feldspars more abundant in the Missisauga Formation (predominantly K-feldspar) than in the Mic Mac Formation (predominantly plagioclase). Feldspar abundance, lithic clasts, and the chemistry of detrital spinels and tourmaline is similar to that found in the Peskowesk A-99 well. Compared to the Lower Missisauga Formation of the Venture and Thebaud fields, chlorite rims on detrital grains are strikingly absent in the coeval and sedimentologically similar Mic Mac Formation sandstones at Louisbourg. Quartz overgrowths are present in almost all sandstones, which also contain early diagenetic kaolinite, likely formed by meteoric water diagenesis. The Fe-silicate precursor of chlorite rims is likely oxidised and destroyed under conditions of meteoric water diagenesis. This study has also shown the occurrence of diagenetic apatite and sphalerite. It suggests that care must be taken in selecting apatite grains for fission track thermochronological analysis. Sphalerite suggests the availability of hot, saline formation waters.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".