Organic matter in an Ocean Continent Transitions of present-day magma-poor rifted margins: the examples of Iberia and Newfoundland
Bibliographic record
Abstract
Abstract: Serpentinisation and concomitant reduction of CO2 to methane at modern hydrothermal vents has been observed to support methanotrophic biosystems at mid-ocean ridges. Exhumation of mantle within ocean regions and its subsequent serpentinisation is a common occurrence. It is possible that methanotrophy is not restricted to hydrothermal vents systems alone and could be pervasive within serpentinised exhumed oceanic mantle. The ocean-continent transition (OCT) of magma-poor rifted continental margins provides an opportunity to investigate this. Serpentinite, intrusive magmatic rocks and overlying sediments collected as part of the Ocean Drilling Program (ODP) from the Iberian and Newfoundland margin, were analysed to find evidence of methanotrophic archaea related to the serpentinisation process. Samples from the OCT of Newfoundland (ODP Leg 210) contain n-alkanes, PAHs and isoprenoids (pristane, phytane) while those from the OCT of Iberian (ODP Legs 149 and 173) also contained detectable steranes and hopanes. However, the distribution and composition of hydrocarbons suggest that the OM may not be indigenous to the rocks. The only clear evidence of Archaea was provided from GDGTs (0 – 3), crenarchaeol and isomers from one sediment sample at the Iberian Margin and these were likely derived from overlying oceanic waters. Hydrocarbon fingerprinting using polar plots suggests that any organic compounds in the igneous and metamorphic rocks were probably introduced from the drilling mud.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".