Palynological dating of the upper part of the De Geerdalen Formation on central parts of Spitsbergen and Hopen
Bibliographic record
Abstract
The Late Triassic is the most problematic period in terms of resolution and age control. The period spans about 36 million years and consists of three stages - Carnian, Norian and Rhaetian. Only four clusters of radiometric age constrain the Triassic time scale (Ogg et al., 2012), and macrofossil data are scarce, hampering exact age determination and biostratigraphic correlation. Additional knowledge on the stratigraphy and geographic ranges of different fossil groups are therefore crucial to build a better framework and thereby contribute in increasing the database. In the Barents Sea area, a huge delta complex reached Eastern Svalbard and Hopen by the end of Late Carnian, and by the end of Late Triassic the paralic deposits had prograded over the northwestern part of the Svalbard Archipelago. Shales, siltstones and sandstones of various thicknesses alternate in the De Geerdalen, Flatsalen and Svenskøya formations, reflecting the deltaic sediments deposited during this period (Riis et al., 2008). Previous studies regarding age datings from Hopen have been conflicting, and a lot of uncertainty is related to the location of the prograding deltafront at any time during this period. Palynological work from two sections, located at Lyngefjellet northeast on Hopen, and from Deltaneset, Central Spitsbergen, resulted in recognition of three assemblages of Late Carnian to ?Middle Norian age. The palynological assemblages are based on spores, pollen, acritarchs and other palynomorphs, and correlation to published records from the Barents Sea area and Arctic Canada have been used for age determination. The lower part of the De Geerdalen Formation section on Hopen is assigned a Late Carnian age based on palynological assemblages similar to the palynofloras recorded in the Barents Sea area and Arctic Canada, and is believed deposited in a deltaic setting reflected in a palynoflora from typical wetland plants. For the upper part of the formation, Early Norian has been suggested based on resemblances to assemblages from the overlying ammonite dated (Korchinskaya, 1982) Flatsalen Formation. The upper section of the De Geerdalen Formation belongs to the Hopen member (Solvi, 2013), herein documented to be equivalent to the Isfjorden Member on Deltaneset, Central Spitsbergen. A coastal environment, probably a delta setting, is suggested for these sections. Svenskøya Formation overlays the Flatsalen Formation and an Early to Middle Norian age is suggested based on the stratigraphically limited taxa, and a delta-setting environment is proposed.
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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| 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".