The continental shelf and rifted continental margins of offshore Newfoundland revisited using constrained 3-D gravity inversions: tracking inheritance trends and rift scars
Bibliographic record
Abstract
<p>The rifted continental margins of Newfoundland represent one of the best-studied examples of non-volcanic/magma-poor margins in the world. In addition to hosting proven prolific resources within the rift basins on the continental shelf, the rifted margins also host many promising frontier regions for oil and gas exploration in both the Flemish Cap and Orphan basins. Prior to rifting and opening of the North Atlantic Ocean during the breakup of Pangaea, the Newfoundland margins lay conjugate to the Iberian margin to the southeast and the Irish Atlantic margin to the northeast. Rifting and breakup evolved from south to north during three rift phases of varying orientation: NW-SE oriented Late Triassic-Early Jurassic rifting between Iberia/Eurasia and North America, W-E oriented Late Jurassic to Early Cretaceous rifting between Eurasia (Ireland) and North America, and SW-NE oriented Late Cretaceous rifting in the Labrador Sea. While the first phase of rifting exploited pre-existing Caledonian-Appalachian basement structures and tectonic fabrics, later rifting reactivated and crosscut these same inherited structures.</p><p>While multichannel seismic reflection imaging has been extensively undertaken across the Newfoundland shelf and rifted margins, deep crustal structure from seismic refraction profiling has been more sparsely constrained. To interpolate between existing crustal-scale seismic refraction profiles, constrained 3-D gravity inversion has previously been undertaken, providing regional constraints on Moho depth, crustal thickness, and beta factors. However, these early inversion attempts suffered from coarse parameterizations of densities within the sedimentary column and an inability to incorporate sparse deep seismic constraints. In this work, we present 3-D density anomaly models for the crust and upper mantle across the Newfoundland margin using constrained 3-D gravity inversions performed using two independent inversion methodologies (minimum structure and probabilistic). Common features to both inversions are deemed robust and provide an improved regional view of the crustal architecture of the offshore margins. In particular, crustal thinning is observed to align with earlier projections of ancient terrane boundaries such as the boundary between the Avalonian terrane and the Meguma terrane at the southeastern limit of the Grand Banks. Furthermore, the derived crustal thicknesses also provide a clear means of delimiting rafted continental fragments, revealing rift trends and the resulting crustal scars. This is particularly evident for the Orphan Basin where the southeastward rotation and displacement of the Flemish Cap has left a trail of orphaned continental pieces. These form crucial components for future deformable plate reconstructions in GPlates and, until then, provide a detailed regional view of the segmentation of the margin during rifting.</p>
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".