What is the age of the Udzha paleorift?: U-Pb age of detrital zircons from Udzha basin terrigenous succession, northern Siberia
Bibliographic record
Abstract
The Udzha paleorift is located between the Anabar and Olenek rivers and is a key structure indicative of the breakup of the Nuna supercontinent. However, the age of initiation and duration of paleorift activity is not defined nowadays. Here we present new U-Pb data for detrital zircons from two terrigenous and volcanic-sedimentary successions of the Udzha sedimentary basin (Unguokhtakh and Udzha Fm), from terrigenous rocks overlying the Udzha basin (Tomtor Fm), and from the sandstone of the lower Mesoproterozoic Mukun Group in the northwest part of Anabar region. The dating results show that sedimentation in the Udzha rift basin began later than ca 1459 Ma, and the duration of the rift activity is estimated as not longer than 73 My. The Udzha rift basin was an isolated basin in the northern part of Siberia, and detrital material came from local sources. A previously unknown source for tuff-sandstone of Unguokhtah Formation with an age of 1850 Ma has been identified, which corresponds by age to the Paleoproterozoic post-orogenic magmatism of the Siberian Craton. In the Neoproterozoic, detrital material of the Tomtor Fm was supplied from the northeast, and the sources were igneous suites of active margin or collision settings. The maximum depositional age of Tomtor Fm is estimated as 565 Ma on the youngest zircon population, which suggests an over 800 Ma gap in sedimentation in northern Siberia in Meso- Neoproterozoic.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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
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