Oligocene North American kinematic change driven by Canary plume activity
Bibliographic record
Abstract
SUMMARY Progressively denser mapping of ocean-floor magnetization has led to detailed reconstructions of past plate motions in the Cenozoic. These reconstructions often reveal rapid kinematic changes that provide crucial information for identifying geodynamic mechanisms that may have caused them, and for quantifying force budgets upon plates. In parallel to these advances, the notion of thin, low-viscosity asthenosphere beneath tectonic plates that facilitates their motions has emerged and consolidated. This weak, mobile layer promotes the formation of the pressure-driven Poiseuille flow that, in turn, generates basal shearing upon plates. In addition, it can be linked to dynamic topography variations due to pulsing plume activity. In this study, we use publicly available finite-rotation compilations of the North American plate (NA) to investigate its kinematic history since Oligocene time. After removing data that are possibly impacted by significant noise, we find that NA experienced a westward speedup near 27 Ma. Next, we explore the role that asthenospheric Poiseuille-type flow caused by increased Canary plume activity may have had in generating this kinematic change. Such plume activity is inferred from the combination of anomalously shallow residual bathymetry and records of past ocean-floor magmatism offshore northwestern Africa. We compare estimates of torque variation upon NA that are (i) required to explain the reconstructed kinematic change, and (ii) predicted by the Poiseuille-type flow associated with the Canary plume activity. Our results indicate that these two torque-variations estimates are in agreement with each other, both in terms of direction and magnitude. This inference suggests that the increased Canary plume activity is a geodynamically-plausible process to explain the Oligocene plate-motion change of NA.
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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 | 0.000 |
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".