Evolution of Precambrian continental lithosphere in Western Canada: results from Lithoprobe studies in Alberta and beyond
Bibliographic record
Abstract
The Precambrian lithosphere of western Canada was assembled into the present crustal configuration between ca. 2.01.78 Ga by plate collisions, sometimes accompanied by arc magmatism, with subsequent cooling of the lithosphere since ca. 1.7 Ga. Collisional processes inferred along preserved plate sutures include (1) subduction of oceanic lithosphere and accretion of Proterozoic arc crust to the western Rae Province; (2) marginal basin consumption and tectonic entrapment of the Hearne Province between coeval subductioncollision zones; and (3) amagmatic marginal basin closure, perhaps analogous to the roots of small collisional orogens, such as the Pyrenees. Seismic reflection profiles acquired during the Lithoprobe Alberta Basement Transect have captured images of syn- to post-collisional structures along these sutures and evidence for crustal-scale thrust imbrication and rigid body accretion of Archean crust with preservation of precollisional tectonic fabric. The degree to which lithospheric mantle beneath Archean crustal blocks was preserved during these collisions is unknown, although tectonic geometries imply significant thermal and (or) mechanical interaction. Post-collisional, intrusive mafic magmatism is imaged widely in both seismic reflection and refraction surveys. These magmatic events are demonstrably Proterozoic, based on crosscutting relationships seen on seismic reflection profiles and geochronology of lower crustal xenoliths, and are comparable in scale to Phanerozoic igneous provinces (e.g., large igneous provinces) but have little preserved surface manifestation. Reactivation of Precambrian basement structures is limited or very subtle, reflecting strength control by the mantle on stress transmission and crustal failure. Long-wavelength elastic deformation of the crust during the Phanerozoic occurred in regions associated with, or adjacent to, Proterozoic mafic magmatism, suggesting local rheologic control of anomalous Phanerozoic paleotopography.
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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".