Lithological, structural, and geochemical characteristics of the Mesoarchean Târtoq greenstone belt, southern West Greenland, and the Chugach – Prince William accretionary complex, southern Alaska: evidence for uniformitarian plate-tectonic processes
Bibliographic record
Abstract
The Mesoarchean Târtoq greenstone belt, southern West Greenland, consists of tectonically imbricated slices of metamorphosed basalt, gabbro, peridotite, and sedimentary rocks and is intruded by felsic rocks (now mylonites) with well-preserved duplex structures, representing a relict accretionary prism. The Târtoq greenstone belt is a remnant of a supra-subduction zone ophiolite that originated as back-arc basin oceanic crust. Following the initiation of intra-oceanic subduction, the back-arc oceanic crust accreted to the overriding plate, forming an accretionary prism. The felsic mylonites are compositionally akin to Archean tonalite–trondhjemite–granodiorite suites. Field observations, along with geochemical and zircon U–Pb age data, indicate that the protoliths of the felsic mylonites were derived from partial melting of back-arc basalts in the accretionary prism and emplaced along thrust faults between 3012 ± 4 and 2993 ± 6 Ma. It is proposed that the partial melting of the basalts likely occurred in response to ridge subduction. The Upper Cretaceous turbiditic greywackes of the Chugach – Prince William accretionary complex in southern Alaska are intruded by Paleogene felsic dykes. These felsic dykes appear to have been derived from partial melting of subducted and (or) accreted oceanic crust during slab window magmatism. Archean granitoid–greenstone terrains share many geological characteristics of Phanerozoic subduction–accretion complexes such as the Alaskan and Altaid subduction–accretion complexes, consistent with the operation of uniformitarian geological processes in the Archean. The Archean Earth might have been dominated by numerous smaller plates and greater ridge length than today that would have resulted in more frequent ridge-accretionary prism interactions and larger volumes of tonalite–trondhjemite–granodiorite generation in subduction–accretion complexes.
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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 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| 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".