Small fractures in marine muds indicating nascent hydrate formation
Bibliographic record
Abstract
On many marine continental slopes, gas hydrate has been observed filling fractures in marine muds. Fracture filling hydrate likely forms because the pore size of clays is small, and therefore, hydrate can only form in secondary porosity; some scientists have suggested the process of hydrate formation causes these fractures to form. On borehole image logs, these fractures were found to have high angles and form in 3D planes. While the plane is filled with hydrate, the overall bulk concentration of hydrate can be quite low. In X-ray computed tomography (XCT) images, similar high angle planar fractures have been found that cut through whole round core. Typically, these fractures appear to have diffuse, wispy edges in comparison to other fractures that form due to core expansion or core collection. We have found new, smaller 3D planer fractures that are likely the initial stages of hydrate fracture formation. These hydrate-filled fractures range in lengths from around 10 – 400 mm with widths ranging from 0.5 - 15 mm. The fractures tend to be well oriented, having a high dip angles (>40°) and going through the whole core on a plane. The wispy, diffused edges suggest sediment displacement due to the hydrate formation process and are distinctly different than other fractures seen in the XCT data. The fractures must be unconnected to any other break in the sediment, existing solely as a fracture with a high dip angle, with diffused edges.In New Zealand, IODP Site 1517, we found that these specific fractures appear near the sulfate-methane transition zone (SMTZ). We hypothesize that if more sediment cores and XCT data were collected through and close to the SMTZ, more similar small fractures would be imaged, potentially indicating nascent gas hydrate formation.
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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 | 0.000 |
| 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) | 0.002 | 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".