FR UTEXITES FROM STROMATOLITES OF THE GUNFLINT IRON
Bibliographic record
Abstract
The microfossil Frutexites is known from many Palaeozoic and some Proterozoic carbonate sedimentary ocks. We recently found unusually well-preserved xamples in the early Proterozoic Gunflint Iron Formation of Ontario, Canada. These are pre-served in chert, along with other microfossils of the Gunflint microbiota. The Gun-flint examples have previously been described as laminated, columnar-branching micro-stromatolites. We have found narrow tubes (interpreted as trichome moulds) axially placed in many of the microcolumns. By comparison with extant organisms, we inter-pret Frutexites as a thick-sheathed scytonematacean cyanophyte. These are the oldest known fossil scytonemataceans. They apparently grew within mats of other micro-organisms. These probably were photosynthetic organisms, which may have significant implications in the interpretation f some occurrences, uch as in the fore-reef facies of Devonian reefs in Western Australia. INTRODUC~ON The Gunflint microbiota from southern Ontario is famous as the first well-preserved assemblage of Precambrian microfossils to be described (see Awramik and Barghoorn, 1977, for references to earlier work}. Its isotopic age is not well established, but is older than 1685 + 24 Ma, and may be approximately 2000 Ma old (for a discussion see Knoll et al., 1978}. The microfossils are organically preserved in dark grey to black cherts, and in-frequently as iron-oxide replacements or casts in red cherts. The dominant taxa are found in both modes of preservation i the Gunflint Iron Formation
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".