Carbonate sedimentation, climate change and stratigraphic completeness on a Miocene cool-water epeiric ramp, Murray Basin, South Australia
Bibliographic record
Abstract
Abstract Lower to Middle Miocene warm temperate-water carbonates of the Murray Supergroup, comprising both fossiliferous heterozoan and foraminifer photozoan facies, accumulated on a low-energy, marine, mesotrophic epeiric ramp in a broad, shallow, intracratonic basin. Depositional conditions ranged from temperate-water with abundant nutrients supplied from the surrounding hinterland under a cool, moist climate regime in the early Miocene, to warm-temperate and subtropical seas with reduced levels of trophic resources associated with an increasingly arid regional climate in the middle Miocene. The succession is separated into three, metre-scale, 1.25–2.75 Ma, transgressive-regressive sequences, or stratigraphic packages. Transgressive carbonates range from Lower Miocene, heterozoan, open-marine echinoidal and bryozoan facies to Middle Miocene, bryozoan-rich, open-marine foraminifer-photozoan facies. Regressive deposits are mainly heterozoan, varying from restricted nearshore marine clays to molluscan seagrass meadow facies, all of which are interpreted to represent highly mesotrophic water conditions. The turn-around from transgression to regression, the transition zone, is variably preserved depending upon the ability of the depositional system to track changes in falling sea-level and is critical to the completeness of the succession. Stratigraphic completeness dramatically increases from the Lower to Middle Miocene stratigraphic packages as rates of sediment production and accumulation increased in conjunction with higher water temperatures and climatic aridity set against a background of increasing eustatic amplitudes. The result is a greenhouse-style succession generated in an evolving icehouse world. This highlights the principle that while allogenic repetition is produced by eustatic forcing, the nature and completeness of the ‘cool-water’ carbonate stratigraphic record can vary significantly due to subtle changes in the nature of the carbonate factory, which are, in turn, determined by sea-water temperature and trophic resources related to climate.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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".