Developing the bedrock layer for Canada 3-D: the Precambrian-Phanerozoic boundary
Notice bibliographique
Résumé
One of the most significant tectonostratigraphic features of the geology of Canada is the boundary separating 'cover' rocks of the Phanerozoic Eon and older 'basement' rocks; dominantly metamorphic and crystalline rocks of the Precambrian shield. In the context of the Canada-3D initiative to develop a 3D geological model of Canada from the surface to the Moho, we have begun to integrate data constraints for modelling this boundary, including geological map, drillhole and seismic data. The 3D surface development is being undertaken through the application of data (geostatistical, implicit modelling (GOCAD/SKUA and SURFE) and knowledge (SPARSE) driven methods. More accurate 3D delineation of this key boundary will help support applications such as the separation of bulk rock properties into cover and basement classes which could in turn be used for geophysical and mineral potential modelling. Coupled with heat flow and fracture density estimates; it could also contribute to future development of national-scale 3D favourability maps for geothermal energy and CO2 sequestration potential. The project combines a large amount of data from various sources collected over the last 175 years since the initiation of geological mapping by the Geological Survey of Canada in 1842 by Sir William Logan. The Precambrian-Phanerozoic boundary is dominantly an angular unconformity between the crystalline bedrock of the Canadian Shield and Phanerozoic sedimentary cover sequences, spanning a hiatus of several hundreds of millions to more than two billion years. In rare cases such as the Rapitan Group in the Mackenzie Mountains, it is a more conformable stratigraphic contact between Neoproterozoic and Cambrian formations. There are also many parts of Canada's subsurface which have no geologic record of the boundary where the crust is mainly composed of either younger Paleozoic and Mesozoic mobile belts (Central Newfoundland and British Columbia), or exposed basement of the Precambrian Shield. The geological data that constrain the Precambrian-Phanerozoic interval are spatially heterogeneous, and vary in quality from excellent observations from petroleum wells in the Western Canada and Williston Basins, to less reliable well logs in Southern Ontario, to interpretive map traces in the overburden covered Hudson Bay low lands. Seismic reflection and refraction data from Lithoprobe and industry surveys will support deeper interpretations of the boundary, and be integrated with constraints obtained by geological mapping in the more complex regions of the Canadian Cordillera and Appalachian orogens. Canada-3D is modelling other tectonostratigraphic features (crustal scale fault networks and major lithostratigraphic horizons) within the bedrock layer, above and below the Precambrian-Phanerozoic boundary, but by focusing early on this significant boundary we gain insight to the data distribution, the required methodology and processing gaps that exist tackling this problem at a national scale. As the project proceeds there will be a need for development of 3D tools to support uncertainty estimation, sparse data interpolation and extension, and interpretation workflows designed to cope with the many challenges presented by limited sampling of complex geologic terrains.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,000 | 0,001 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,002 | 0,001 |
| Science ouverte | 0,001 | 0,002 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,010 | 0,002 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».