METAZOAN REEF CONSTRUCTION IN A MIDDLE ORDOVICIAN SEASCAPE: A CASE STUDY FROM THE MINGAN ARCHIPELAGO, QUEBEC
Bibliographic record
Abstract
ABSTRACT The Ordovician (485–444 Ma) saw a global shift from microbial- to skeletal-dominated reefs, and the rise of corals and bryozoans as important reef-builders. Hypothetically, increasingly morphologically diverse and abundant reef-building metazoans increased spatial habitat heterogeneity in reef environments, an important component of reefs' capacity to support diverse communities. Quantifying the spatial scale and extent of this heterogeneity requires three-dimensional exposures of well-preserved reefs whose composition and spatial arrangement can be measured. The Darriwilian (c. 467–458 Ma) carbonate sequence of the Mingan Archipelago, Quebec, presents such exposures, and also provides an opportunity to establish how the distribution of skeletal-dominated metazoan reefs contributed to, and was influenced by, seafloor relief. This study includes two transects through a 200–300 m wide paleo-reef belt, which developed along a rocky paleo-coast line. The reefs are typically micrite-rich, meter-scale mounds, locally forming larger complexes. Here, we present quantitative evaluations of the composition of these reefs, and detailed mapping of reef distributions. There is high compositional heterogeneity between reefs at spatial scales ranging from meters to kilometers, contributed by differences in the volumetric contribution of skeletal material to the reef core, and in the identity of the dominant reef-builders. We suggest that the abundance and morphological diversity of Middle Ordovician reef building metazoans made them important contributors to environmental and substrate heterogeneity, likely enhancing the diversity of reef-dwelling communities.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.005 |
| Science and technology studies | 0.005 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".