Salt Tectonics and Hydrocarbon Accumulations Trapped on Diapir Flanks in the Lusitanian Basin, Portugal
Bibliographic record
Abstract
Abstract Salt movement in the Lusitanian basin has significantly affected sedimentation in the onshore portion of the basin. We show that salt diapirism initiated soon after deposition of the salt in the Hettangian and that diapirism was active throughout the Jurassic and Cretaceous periods. Strong Alpine-age inversion produced squeezing of the diapirs and folding and faulting in the overburden around the salt structures. Large upturned flanks of overburden sediments were produced and constitute good potential traps for hydrocarbon accumulations. We describe two upturned diapir flanks which are superbly exposed on coastal cliffs. Both the São Pedro de Moel and Santa Cruz structures contain tar-saturated reservoirs, trapped against salt diapir walls. We interpret these to be exhumed but now biodegraded, oil accumulations. The São Pedro de Moel structure is estimated to contain >85 million barrels of tar and demonstrates that there is a commercially viable hydrocarbon system in the basin, although most of the traps onshore have been breached during inversion. This has positive implications for the deeper offshore Lusitanian and Peniche basins, as well as the conjugate Carson-Bonnition basin in Newfoundland. To our knowledge these are the only documented examples of exposed hydrocarbon accumulations trapped against salt diapir flanks and could represent the first bygone oil accumulations described in the Lusitanian basin.
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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 | 0.001 |
| 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 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".