Thermochemical oil formation and the search for a subsurface biosphere hydrocarbon fingerprint in hydrothermal vent sediments at Guaymas Basin, Gulf of California
Bibliographic record
Abstract
For this study a biomarker survey and multi-molecular chemometric analysis was performed on petroleum-rich sediments from the Cathedral Hill hydrothermal vent site in Guaymas Basin, Gulf of California.The objective of this study was to monitor the progression of petrogenesis, biological activity, and migration of hydrocarbons along a natural geothermal gradient (spanning 0-155 °C) intersected by a push core transect.Biodegradation increases down-core to variable degrees across the transect, while decoupled ratios of bacterial-sourced lipids such as hopene and hopane mark the transition zone of subsurface bacterial habitability.Various proxies show maturity increases with depth and proximity to the vent-center.These parameters, along with chemometric models, subtracted chromatograms, and hydrocarbon diversity measurements reveals that hydrocarbon generation likely begins where vent temperatures surpass 110 °C.This results in even shallower, 8-10 centimeters below seafloor, generation from what is predicted by kinetic models.The results suggest the vent temperatures may vary over time or that other applied geochemical factors (e.g.vent chemistry) may influence catagenesis.Overall, the results indicate marked spatial diversity and complexity in this sedimented hydrothermal site.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".