As it ever was: Calcium isotope constraints on Mesoarchean seawater chemistry
Bibliographic record
Abstract
Abstract Earth’s long-term climate is closely tied to the formation of carbonate sediments in the ocean, driving the ocean’s ability to moderate atmospheric CO2 levels. It has been hypothesized that in the Precambrian, this process was controlled by a “hidden” deep-sea carbonate sink. However, our results indicate that shallow-marine platforms have been the dominant mode of carbonate formation since the Mesoarchean. This conclusion is based on Ca isotopes from 2.8 Ga carbonates, which constrain the Ca isotope value of Mesoarchean seawater to −0.5‰ relative to modern values, strikingly similar to pre-Mesozoic values and suggesting that carbonate deposition mainly was confined to shallow-water platforms until the evolution of pelagic calcifiers in the Mesozoic.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.010 | 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 teacher head, 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".