Seismic signal penetration beneath postrift sills on the Newfoundland rifted margin
Bibliographic record
Abstract
Abstract Analysis of averaged, smoothed instantaneous frequency and amplitude of seismic-reflection data collected on the Newfoundland magma-starved rifted margin along the Ocean Drilling Program (ODP) leg 210 transect demonstrate that the transparency of “transitional” crust arises from poor signal penetration. In principle, the high-frequency spectral content and amplitude of seismic reflection data should decrease with increasing traveltime as a result of absorption, geometric spreading, and scattering so long as seismic energy continues to return from deeper levels of the subsurface. As a result, if average frequency and amplitude cease to decrease with depth, background noise, rather than returning seismic energy, likely dominates the record. Average frequency increases and average amplitude remains comparatively constant below bright reflections overlying transitional crust on the Newfoundland margin. Similar patterns are not observed at the sediment-basement contact farther seaward in oceanic crust where intracrustal reflections are apparent. In thoserecords, both amplitude and frequency continue to decrease steadily for at least 2–3s below the top of basement. We interpret these observations as evidence that signal penetration is comparatively poor beneath bright reflections overlying transitional basement. Consequently, the featureless appearance of transitional crust on the Newfoundland margin in seismic-reflection profiles cannot be used to make inferences about its physical properties; instead, only seismic characteristics observed in rare basement highs that rise above bright reflections in the lowermost sedimentary section can provide meaningful information. Weak signal penetration in this crustal domain is consistent with the results from site 1276 during ODP leg 210, where interlayered diabase sills and sediments were recovered above basement, which would be expected to result in high reflection coefficients and low signal penetration. The apparent lack of seismic penetration throughout the transition zone off Newfoundland also implies interlayered sills and sediments might be widespread over this crustal domain.
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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) | 0.001 | 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; 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".