Geology of the Nain Complex, Labrador, Canada: Occurrence of the Early Archean Supracrustals
Bibliographic record
Abstract
The Hadean is the most mysterious period because no rocks and\ngeologic bodies are preserved except for only the zircons in\nWestern Australia, Canada, China and Greenland [1]. But, it is the\nmost important period because the early evolution possibly clinched\nthe earth’s history. We try to find the earliest supracrustal rocks in\nthe world to investigate the Hadean tectonics. As far, the oldest\nsupracrustal rocks are found in Akilia association in West\nGreenland, Nuvvuagittuq in Quebec, and Nain Complex in Labrador\n[2,3].\nWe made geological survey in the Nain Complex, and\nreinvestigated the occurrence of the supracrustal rocks and their\nrelationship with the ambient orthogneisses. Previous works focused\non distribution of the supracrustal belts within the orthogneisses\n[e.g. 4], but the detailed field occurrence of the supracrustal rocks\nwithin the belts is still ambiguous. Therefore, we focus on their\ninternal structures.\nThe supracrustal belts are repeatedly intruded by granitic\nintrusions with some ages and their original structures are obscured,\nbut their lithostratigraphies are relatively well preserved in Nulliak,\nBig and Shuldham islands and St Jones Harbor. The supracrustal\nbelts in Nulliak and Big islands comprise ultramafic rocks, mafic\nrocks and mafic sediments intercalated with feldspathic sediments\nand banded iron formations in ascending order. In the St Jones\nHarbor, it is composed of ultramafic rocks, mafic rocks, banded iron\nformation, and clastic sediments, intercalated with chert in the\nmiddle and with bedded carbonate rocks in the upper part,\nrespectively, in ascending order. In the Shuldham Island, it consists\nof ultramafic rocks, layered gabbro with precursors of plagioclase\nand pyroxene accumulation layers, mafic rocks and terrigenous\nsediments in ascending order. The lithostratigraphies are very\nsimilar to oceanic plate stratigraphy. The fact that some supracrustal\nbelts are intruded by Uivak I orthogneisses and presence of >3.86\nGa zircons in the supracrustal rocks [e.g. 3] suggest that the\nsupracrustal belts have early Archean ages. In addition, despite of the\nstill ambiguous relationship between Nanok Gneiss and supracrustal\nrocks, presence of Nanok Gneiss (3.85 to 3.91 Ga) in this area [5]\nimplies that the supracrustal belts date back to the earliest Archean.\n[1] Froude et al. (1983) Nature 304, 616-618; Nelson et al.\n(2000) EPSL 181, 89-102; Mojzsis & Harrison (2002) EPSL 202,\n563-576; Iizuka et al. (2006) Geology 34, 245-248; Wang et al.\n(2007) CSB 52, 3002-3010. [2] Bowring & Williams (1999) CMP\n134, 3-16; Nutman et al. (1996) Precamb. Res. 78, 1-39; O'Neil et\nal. (2008) Science 321, 1828-1831. [3] Schiøtte et al. (1989) Can\nJour Earth Sci. 26, 2636-2644. [4] Bridgwater et al. (1974) Geol\nSurv Canada, Paper 75-1 Part A, 282-296. [5] Collerson (1983)\nin Abstracts for Early Crustal Genesis Field Workshop, LPI,
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.004 | 0.006 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".