Provenance of the uppermost clastic rocks of the Lower Cretaceous Kezilesu Group from the Ulugqat Basin, Xinjiang, NW China and its tectonic implications: Insights from sedimentary records and detrital zircon U–Pb geochronology
Bibliographic record
Abstract
The Ulugqat Basin is located at the juncture of the Tarim Basin, the western Tianshan Orogen of the Central Asian Orogenic Belt, and the Pamir salient of the Tethys domain. A comprehensive provenance study using sedimentology, petrology, and detrital zircon U–Pb geochronology was carried out on the clastic rocks of the fifth member of the Lower Cretaceous Kezilesu Group from the Ulugqat Basin, aiming to better understand the nature of its relationships with the neighbouring tectonic units as well as the formation of sandstone‐hosted Zn–Pb mineralization. The fifth member consists of conglomerate, gravelly sandstone, sandstone, and mudstone interbeds, and is interpreted as alluvial fan–braid river–braid river delta sediments. The conglomerate and gravelly sandstone contain different kinds of lithic fragments, including phyllite, quartzite, chert, chalcedony, and some felsic igneous rocks, with low compositional maturities. The detrital zircon U–Pb ages of sandstone from the uppermost part of the fifth member range widely from 229.7 to 2,984.9 Ma, concentratedly distributed in five groups: 230–300, 390–480, 750–880, 1,600–2,200, and 2,300–3,000 Ma. The identified palaeocurrent directions, heavy mineral assemblages, specific provenance indicators, and distributions of detrital zircon U–Pb ages all indicate that these clastic rocks are probably sourced from the South Tianshan Orogen to the north, rather than the Pamir salient, probably involving the Proterozoic Aksu metamorphic rocks, Palaeozoic sedimentary rocks, Late Carboniferous–Early Permian alkali granite, and some mafic/ultramafic rocks of ophiolitic mélange. This interpretation is consistent with a late Early Cretaceous uplifting of the South Tianshan Orogen according to previous low‐temperature thermochronological data sets. The thick deposition of these Lower Cretaceous clastic rocks and associated uplifting of the South Tianshan Orogen are interpreted to be related to the coeval collision of the Karakoram–Lhasa Block with the southern Asian margin.
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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 | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| 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
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), 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".