Internal fabric of giant domes in the Mesoarchean Steep Rock carbonate platform, Superior Province, Canada
Bibliographic record
Abstract
Drivers for accumulation of Archean seafloor carbonate were mostly very different than those operating today. Alternating crystal fan fabric and cuspate fenestral fabric forming metre-scale giant domes is rare in Archean carbonate platforms and limited to this time period. Their genesis is poorly understood. The oldest known examples are in the 2.8 Ga Steep Rock Group of northwestern Ontario, Canada, where 200–500 m of carbonate was deposited on a semirestricted platform. Here the elongate domes are composed of centimetre to decimetre alternations of calcite crystal fans and microbialite, commonly separated by thin, dark ferroan dolomite and quartz replaced areas, which have herein been referred to as alteration surfaces. The cuspate fenestral fabric is formed of draping, mat-like laminae, vertically oriented support structures, and cement-filled voids. The concave-up mat-like laminae attach to the support structures, which, similar to the alteration surfaces, are primarily composed of ferroan dolomite and quartz. One bedding plane surface consisted of centimetre-scale polygonal blocks with upturned edges with support structures forming the cracks, leading to the possibility that desiccation may be involved in at least this layer’s development. As opposed to the calcite microbialite the crystal fan layers were probably originally aragonite, containing significantly higher Sr contents with less Fe and Mn. This necessitates changes in water geochemistry during deposition of the alternating layers. Possible drivers could be: (i) relative sea-level changes controlling amount of isolation, (ii) calcite precipitation changing the Mg/Ca ratio, (iii) changes in organic productivity laterally moving the redox gradient, (iv) a change in Fe2+ concentration, and (v) storm events causing water body mixing.
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 | 0.002 |
| Science and technology studies | 0.002 | 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) | 0.002 | 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".