Hydrogen isotopes of lignin-methoxy groups from Neogene sub-fossil wood in the Canadian Arctic
Bibliographic record
Abstract
Sub-fossil wood samples were obtained from existing sub-fossil wood collections described in previous studies (Csank et al., 2011, 2013; Devaney et al, 1991; Fyles et al., 1990, 1994, 1998; Williams et al., 2008). The number of samples analysed varies depending on site – Banks Island Ballast Brook Formation (n = 10), Banks Island Beaufort Formation (n = 9), Prince Patrick Island (n = 5), Meighen Island (n = 5), Ellesmere Island Fyles Leaf Bed and Beaver Pond (n = 9) and Bylot Island (n = 5). Each sample represents a full or partial cross-section of a tree, with an average of 53 rings per sample. In the lab, a representative sub-sample (integrating all rings) was collected from each of the independent tree samples, and homogenised to a fine powder. The powdered wood was then placed in a crimped vial for chemical reaction with hydroiodic acid, which converts lignin-methoxy groups in the sample to gaseous methyl iodide (CH3I). The ratio of 2H/1H (d2H) of the CH3I gas in the headspace of the vials was measured by Gas Chromatography-Isotope Ratio Mass Spectrometry (GC-IRMS) at the University of Heidelberg in Germany. The d2H measurements were normalised to the Vienna Standard Mean Ocean Water scale and are reported in units of permille. All samples were analysed in quadruplicate and the average measurement precision is less than 2 permille. The site-averaged d2H lignin-methoxy values indicate precipitation d2H values were +33 to +60 permile higher than today, which is explained by a mean climate that was +8.6 to +15.6°C warmer than today assuming the modern d2Hprecip-temperature sensitivity is a reasonable assumption for the past. This research provides new information about the Neogene Arctic climate. These data be used to understand the mean climate sensitivity the Arctic (including slow feedbacks) and help to improve our ability to predict of future climate change at high latitudes. References: [1] Csank et al. 2011. Palaeogeogr. Palaeoclimatol. Palaeoecol. 308, 339–349. [2] Csank et al., 2013. Palaeogeogr. Palaeoclimatol. Palaeoecol. 369, 313–322. [3] Devaney, J., 1991. Arctic 206–216. [4] Fyles, 1990. Arctic. https://doi.org/10.2307/40510962. [5] Fyles et al. 1994. Quat. Int. 22–23, 141–171. [6] Fyles et al. 1998. Geol. Surv. Canada Bull. 512. [7] Williams et al. 2008. Palaeogeogr. Palaeoclimatol. Palaeoecol. 261, 60–176.
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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 | 0.003 | 0.003 |
| Science and technology studies | 0.003 | 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) | 0.002 | 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".