Iron Isotope Characteristics of Hot Springs at Chocolate Pots, Yellowstone National Park
Bibliographic record
Abstract
Chocolate Pots Hot Springs in Yellowstone National Park is a hydrothermal system that contains high aqueous ferrous iron [∼0.1 mM Fe(II)] at circumneutral pH conditions. This site provides an ideal field environment in which to test our understanding of Fe isotope fractionations derived from laboratory experiments. The Fe(III) oxides, mainly produced through Fe(II) oxidation by oxygen in the atmosphere, have high ⁵⁶Fe/⁵⁴Fe ratios compared with the aqueous Fe(II). However, the degree of fractionation is less than that expected in a closed system at isotopic equilibrium. We suggest two explanations for the observed Fe isotope compositions. One is that light Fe isotopes partition into a sorbed component and precipitate out on the Fe(III) oxide surfaces in the presence of silica. The other explanation is internal regeneration of isotopically heavy Fe(II) via dissimilatory Fe(III) reduction farther down the flow path as well as deeper within the mat materials. These findings provide evidence that silica plays an important role in governing Fe isotope fractionation factors between reduced and oxidized Fe. Under conditions of low ambient oxygen, such as may be found on early Earth or Mars, significantly larger Fe isotope variations are predicted, reflecting the more likely attainment of Fe isotope equilibrium associated with slower oxidation rates under low-O₂ conditions.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.017 | 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; both teacher heads agree on what is shown here.
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".