Very low-grade metamorphism of the Dezadeash flysch (Jura-Cretaceous): Constraints on the burial history of the Nutzotin-Dezadeash basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon
Bibliographic record
Abstract
Secondary mineral assemblages in sandstone and tuff indicate high temperature zeolite facies metamorphism; Kübler indicies of illite and Árkai indicies of chlorite in mudstone record diagenetic to high anchizone metapelitic conditions; and pyrolysis of organic matter and the color of organic matter (i.e., the Thermal Alteration Index of palynomorphs and the Conodont Alteration Index) in mudstone and hemipelagite beds suggest thermal maturation reached catagenesis to mesogenesis stages. Collectively, the mineralogic and organic thermal indicators suggest the Dezadesh Formation was subject to pressure-temperature (P-T) conditions of 2.5 kbar and 250 °C. The estimated P-T conditions, together with published thermochronometric data, shows that the Dezadeash Formation underwent rapid, short-term heating followed by gradual, long-term cooling. Moreover, a calculated tectonic subsidence curve indicates rapid, short-term subsidence, followed by gradual, long-term uplift. Secondary clay minerals associated with heating and subsidence are characterized by a restricted assemblage dominated by 2M 1 illite and chlorite. The thermal history, subsidence history, and secondary clay mineral assemblage are not supportive of deposition in peripheral foreland, backarc, strike-slip, and rift basins; nor are the results corroborative with previous deformation and crustal-scale reconstructions depicting the Dezadeash Formation being underthrust >20 km beneath the Blanchard River assemblage, Kluane Schist, and Yukon composite terrane (YCT). The Dezadeash-Nutzotin basin contrasts sharply with the contemporaneous Gravina belt and Gravina sequence in southeastern Alaska that were apparently underthrust >20 km beneath the YCT. The contrasting tectono-metamorphic histories may be a manifestation of oblique collision and diachronous, south-to-north accretion of the Chitina arc and WCT to YTC.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".