Detrital zircon U-Pb and Lu-Hf analysis of Paleozoic sedimentary rocks from the Pearya terrane and Ellesmerian Fold Belt (northern Ellesmere Island): A comparison with Circum-Arctic datasets and their implications on terrane tectonics
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Bibliographic record
Abstract
ABSTRACT Detrital zircon U-Pb and Hf isotopic data from Ordovician to Devonian–Carboniferous sedimentary rocks sampled from the Pearya terrane and adjacent areas, northern Ellesmere Island, record temporal variation in detrital zircon signature on the northeastern Arctic margin of Laurentia. Ordovician to Silurian clastic sediments deposited on the Pearya terrane record a provenance signal from before terrane accretion. This signal is dominated by Ordovician arc material and grains derived from recycling of Proterozoic metasedimentary and metaigneous basement. This pattern is similar to Neoproterozoic detrital zircon spectra from the Svalbard and East Greenland Caledonides, supporting the exotic nature of the Pearya terrane and links between Pearya and the Arctic Caledonides. Sedimentary rock deposited in the late Ordovician and early Silurian deep water basin of the Clements Markham fold belt likewise record a recycled source containing abundant early Neoproterozoic and Mesoproterozoic aged zircon. This contrasts with similarly aged units on Franklinian shelf, which contain much more abundant Paleoproterozoic zircon ages. The provenance of the late Devonian–Carboniferous(?) Okse Bay Formation is dominated by sediment reworked from the units exposed in Pearya or the East Greenland Caledonides, with new sources derived from Paleoproterozoic domains of the Canadian-Greenland shield and late Devonian igneous rocks documented in Ellesmere and Axel Heiberg Islands, and Arctic Alaska. In contrast, detrital zircon age spectra from Devonian sedimentary rocks in the western Ellesmerian Clastic Wedge and northern Cordilleran clastic wedge of the Mackenzie Mountains contain abundant zircon grains yielding ages characteristic of the Caledonian and Timanian Orogens. This contrast suggests that the northeastern and northwestern sectors of the Paleozoic Laurentian Arctic margin received sediments from different terranes, with the northeast being dominated by reworked Caledonide terrane and Laurentian craton detritus, and the northwest likely receiving sediment from elements of Arctic Alaska–Chukotka. These detrital zircon data indicate that the Pearya terrane was isolated from northern Laurentia until after the late Silurian. The accretion of the Pearya terrane is constrained between the late Silurian and middle Devonian by stratigraphy, detrital zircon provenance shifts indicating a Laurentian cratonic source by the early Carboniferous, metamorphism in the orthogneiss basement observed between ca. 395 and 372 Ma, and the emplacement of the Cape Woods post-tectonic pluton at 390 Ma.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
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score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it