Postrift Development of the Eastern North American Margin: Early Cretaceous Intraplate Magmatism and Normal Faulting of Western Vermont and Eastern New York
Bibliographic record
Abstract
The passive eastern North American margin has undergone episodes of intraplate magmatism, normal faulting, and uplift, yet driving mechanisms are not well understood. The Early Cretaceous magmatism of the New England-Quebec (NEQ) igneous province is a well-known example of postrift magmatism along the margin. Sheet intrusions and small plutons of the New England NEQ are concentrated in western Vermont and eastern New York and geographically associated with mesoscale normal faults. Traditionally, the NEQ has been attributed to the Great Meteor hotspot or reactivation of structurally weakened lithosphere. Recent work on Cretaceous uplift across New England, however, has pointed toward edge-driven convection as a driving mechanism for the uplift, and geophysical observations indicate the process of edge-driven convection is occurring beneath New England today. The research presented in this dissertation evaluates edge-driven convection as a potential driving mechanism capable of explaining the observations of postrift magmatism and normal faulting in western Vermont and eastern New York. Geochronological and geochemical data for the NEQ of western Vermont and eastern New York were obtained to understand the timing and characteristics of the Early Cretaceous magmatism. To investigate the potential crustal expression of edge-driven convection, the Early Cretaceous stress field was characterized using paleostress inversion of mesoscale fault-slip data. 40Ar/39Ar and U–Pb LA-ICP-MS geochronology for the sheet intrusions and Cuttingsville complex indicates magmatism was episodic and spanned at least 35 m.y. over a distance of ~100 km. Trace element and rare earth element signatures of the alkaline magmatism indicate a common source for the magmatism through time. Paleostress inversion of mesoscale fault-slip data, analysis of sheet intrusion geometry, and field observations indicate N–S and NW–SE extension occurred in association with magmatism as perturbations to the regional NE–SW extensional stress field. Timing is constrained by crosscutting relationships and the compatibility of the stress fields associated with normal faulting and sheet intrusion geometry. The geochronological and geochemical results are inconsistent with a hotspot origin and best explained by edge-driven convection while the normal faulting and extensional events are interpreted as the crustal expression of edge-driven convection.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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 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".