Birth and death of a triple junction: The example of the Bay of Biscay
Bibliographic record
Abstract
The Bay of Biscay fossil triple junction separated three tectonic plates: North America, Europe and Iberia. It is defined by three pairs of conjugate margins: Armorican-North Iberian margins, the Goban Spur-Flemish Cap margins, and the West Iberia-Newfoundland margins. In this area, although it was proposed that steady-state spreading started in Aptian/Albian times and ceased around 80 Ma (Verhoef et al., 1986), the timing and opening directions during rifting and spreading remain uncertain. Indeed, oceanic magnetic isochrones are badly constrained. Moreover, exhumed mantle is exposed, so the Ocean-Continent Transition (OCT) of the three conjugate margins is difficult to localize (Boillot et al., 1988; Sibuet et al., 2007; Thinon, 1999; Tugend et al., 2015). As a result, there is no consensus on kinematic reconstructions.This work, in the context of my PhD thesis, is part of the ANR project “FirstMove”. It is based on a multidisciplinary approach using geological data (wells, dives) and geophysical data (seismic reflection, magnetic, gravity and bathymetry data). Notably, we integrate the Breogham seismic reflection profiles which cross the fossil spreading ridge. We aim to redefine, map and date the different rift domains (necking, hyperextended, exhumed mantle and oceanic domains), in order to better constraint the evolution of the Bay of Biscay triple junction. Indeed, the Iberia plate kinematic is a keystone to understand the global kinematic of the whole Atlantic-Tethys system. Boillot, G., Winterer, E. L., & et al. (Eds.). (1988). Proceedings of the Ocean Drilling Program, 103 Scientific Results (Vol. 103). Ocean Drilling Program. https://doi.org/10.2973/odp.proc.sr.103.1988Sibuet, J., Srivastava, S., & Manatschal, G. (2007). Exhumed mantle‐forming transitional crust in the Newfoundland‐Iberia rift and associated magnetic anomalies. Journal of Geophysical Research: Solid Earth, 112(B6), 2005JB003856. https://doi.org/10.1029/2005JB003856Thinon, I. (1999). Structure profonde de la Marge Nord Gascogne et du Bassin Armoricain. Ifremer-IUEM, Brest, France.Tugend, J., Manatschal, G., Kusznir, N. J., & Masini, E. (2015). Characterizing and identifying structural domains at rifted continental margins: application to the Bay of Biscay margins and its Western Pyrenean fossil remnants. Geological Society, London, Special Publications, 413(1), 171–203. https://doi.org/10.1144/SP413.3Verhoef, J., Collette, B. J., Miles, P. R., Searle, R. C., Sibuet, J.-C., & Williams, C. A. (1986). Magnetic anomalies in the northeast Atlantic Ocean (35°-50° N). Marine Geophysical Researches, 8(1), 1–25. https://doi.org/10.1007/BF02424825
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.005 | 0.004 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.003 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 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".