Tectonic evolution of northern Ellesmere Island: insights from the Pearya Terrane, Ellesmerian Clastic Wedge And Sverdrup Basin
Notice bibliographique
Résumé
The tectonic evolution of northern Ellesmere Island is dominated by the accretion of the Pearya Terrane and the progressive reworking of materials from the Pearya Terrane and the northern Caledonides. Geochronology from a suite of seven Succession I orthogneiss samples defines a range of earliest Neoproterozoic ages from 962 ± 6 Ma to 974 ± 8 Ma. Geochemistry of both zircon and whole rock samples reveal a complex magmatic history tapping multiple sources. The rocks include both I and S type granitoids, with silica contents ranging from 62% to 73%. Trace element geochemistry reveals LILE enrichment decoupled from low to depleted HFSE values, suggestive of an origin above a subduction zone. Isotope geochemistry supports input from juvenile and evolved materials, with εNd(i) values between -1 and -4.6, and a similar range for εHf from zircon. The northern elements of the Caledonian Orogen preserve a record of magmatism in the c. 985 Ma to 920 Ma range. These ages are also observed in orthogneiss units of the south central Brooks Range and Farewell terrane, Alaska. The Pearya Terrane orthogneiss units and those currently dispersed in Alaska are interpreted to have originated near or on the eastern margin of Greenland and record post-Rodinia assembly subduction outboard of the supercontinent.\nSuccession II (Trettin, 1987) of the Pearya Terrane represents variably metamorphosed metasedimentary rocks of Proterozoic to early Paleozoic age. These units are structurally juxtaposed with Succession I orthogneiss and Paleozoic sedimentary units of the Pearya Terrane. Detrital zircon age spectra from seven samples of Neoproterozoic meta-sedimentary rocks reveal three groups defined by observed dominant age peaks and youngest observed age populations. Group I includes three quartzite samples and contains numerous c. 1100 Ma to 1800 Ma peaks, with the youngest population at c. 1050 Ma. Two samples of immature meta-sandstone form Group II, defined by a dominant c. 970 Ma age peak. Two samples from the diamictite unit below the Deutchers Glacier thrusts form Group III, with a similar pattern of c. 1000 Ma to 1800 Ma age peaks to Group I; however, this group includes a small population of c. 600 Ma to 700 Ma grains as well. The ubiquitous Mesoproterozoic ages reflect a Grenvillian-Sveconorwegian provenance. These data are consistent with detrital zircon datasets from other North Atlantic-Arctic Caledonide terranes, reinforcing stratigraphic links between the Pearya Terrane and the northern Caledonides. The utility of the Pearya Terrane dataset is multiplied by probable links to Circum-Arctic and Cordilleran terranes, many of which contain similar populations of Mesoproterozic-aged detrital zircon.\nU/Pb ages and Hf isotopic data from detrital zircon suites sampled from Ordovician to Carboniferous sedimentary rock of the Pearya Terrane and northern Ellesmere Island record define the background for terranes translating along the northeastern Laurentian margin in the Paleozoic. Ordovician to Silurian clastic sediments deposited on the Pearya Terrane record pre terrane accretion provenance dominated by recycling of the metaigneous and metasedimentary Proterozoic basement as well as an Ordovician arc source. The provenance of Late Devonian sediments deposited during the Ellesmerian Orogen is dominated by similar recycled materials, with new sources derived from Paleoproterozoic domains of the Canadian-Greenland shield and documented late Devonian granitoids emplaced the Canadian Arctic Islands and Arctic Alaska. The basal Sverdrup Basin records increasing proportions of Paleoprtoerozoic and Archean aged grains relative to Mesoproterozoic ages, suggestive of increased contributions from the Laurentian craton and no little detritus exotic to Laurentia. Detrital zircon age spectra from Devonian to Carboniferous sediments in the northern Cordilleran clastic wedge and western Canadian Arctic Islands contain abundant exotic zircon likely derived from the Caledonian and Timanian Orogens. This variance of sediment provenance indicates that the eastern Canadian Arctic Island were isolated from non-Laurentian or Caledonian detritus, and that sources of the exotic Timanian zircon reconstruct farther west along the margin.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
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 tête enseignante, 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 ».