Biostratigraphic correlation of Lower Cretaceous – Neogene successions from Labrador Sea, Canada in the south to Svartenhuk Halvø, West Greenland in the north
Bibliographic record
Abstract
Over the past 20 years intensive palynological studies of Cretaceous to Neogene successions on- and offshore West Greenland have been carried out by GEUS. In the early nineties GGU (the former Geological Survey of Greenland) focused on sequence stratigraphic analysis of the Cretaceous sediments in West Greenland and a Cretaceous palynostratigraphy was established for the Disko–Nuussuaq–Svartenhuk Halvo area based on 29 surface sections and 12 shallow boreholes (Nohr-Hansen 1996). The stratigraphy was tested and extended with data from the stratigraphic borehole Umiivik-1 on Svartenhuk Halvo (Dam et al. 1998), and the change in the palynological assemblage across the K/T boundary on Nuussuaq was described by Nohr-Hansen and Dam (1997). Fieldwork continued and the discovery of oil seepages in the Palaeogene volcanic succession attracted the industry and several exploration wells were drilled (and abandoned) onshore Nuussuaq in 1995 and 1996, providing new data on the pre-basaltic Paleocene biostratigraphy (Nohr-Hansen et al. 2002). New offshore concessions in West Greenland led to requests for new biostratigraphic studies of the exploration wells drilled in 1976 and 1977. A Palaeogene dinocyst biostratigraphy for the 5 old offshore wells and the Qulleq-1 well drilled in 2000 was described by Nohr-Hansen (2003). Further commercial interest in the area led to a regional correlation study of the Mesozoic–Palaeogene sequences across the Greenland–Canadian boundary. The study included new data from 6 selected Canadian wells from the Labrador Sea and led to a detailed Cretaceous palynostratigraphy. Over the past five years, GEUS and the Geological Survey of Canada (Atlantic) have cooperated and expanded the regional palynological study with additional 5 wells from the Labrador Sea, resulting in a more detailed age control based on more than 2000 samples from 17 offshore wells. This major correlation project (in prep. for a GEUS bulletin) has mapped out palaeoenviroment, Azolla blooms, local and regional hiati, and 106 bioevents have been identified for the Cretaceous to Neogene succession deposited in the Labrador–Baffin seaway. Dam, G., Nohr-Hansen, H., Christiansen, F. G., Boejesen-Koefoed, J. and Laier, T. (1998). The oldest marine Cretaceous sediments in West Greenland (Umiivik-1 borehole) - record of the Cenomanian–Turonian Anoxic Event?. Geology of Greenland Survey Bulletin 180 , 128–137. Nohr-Hansen, H. (1996). Upper Cretaceous dinoflagellate cyst stratigraphy, onshore West Greenland. Bulletin Gronlands geologiske Undersogelse 170 , 104 pp. Nohr-Hansen, H. (2003). Dinoflagellate cyst stratigraphy of the Palaeogene strata from the Hellefisk-1, Ikermiut-1, Kangâmiut-1, Nukik-1, Nukik-2 and Qulleq-1 wells, offshore West Greenland. Marine and Petroleum Geology 20 , 987–1016. Nohr-Hansen, H. and Dam, G. (1997). Palynology and sedimentology across a new marine Cretaceous/Tertiary boundary section on Nuussuaq, West Greenland. Geology 25:9 , 851–854 Nohr-Hansen, H., Sheldon, E. and Dam, G. (2002). A new biostratigraphic scheme for the Paleocene onshore West Greenland and its implications for the timing of the pre-volcanic evolution. In Jolley, D.W. & Bell, B.R. (eds) The North Atlantic Igneous Province: Stratigraphy, Tectonic, Volcanic and Magmatic Processes . Geological Society, London. Special Publication 197 , 111–156.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| 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".