Paleosol barometer indicates extreme fluctuations in atmospheric CO2 across the Cretaceous-Tertiary boundary
Bibliographic record
Abstract
Research Article| August 01, 2002 Paleosol barometer indicates extreme fluctuations in atmospheric CO2 across the Cretaceous-Tertiary boundary Lee Nordt; Lee Nordt 1Department of Geology, Baylor University, Waco, Texas 76798, USA Search for other works by this author on: GSW Google Scholar Stacy Atchley; Stacy Atchley 1Department of Geology, Baylor University, Waco, Texas 76798, USA Search for other works by this author on: GSW Google Scholar S.I. Dworkin S.I. Dworkin 1Department of Geology, Baylor University, Waco, Texas 76798, USA Search for other works by this author on: GSW Google Scholar Geology (2002) 30 (8): 703–706. https://doi.org/10.1130/0091-7613(2002)030<0703:PBIEFI>2.0.CO;2 Article history received: 18 Jan 2002 rev-recd: 22 Apr 2002 accepted: 30 Apr 2002 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Lee Nordt, Stacy Atchley, S.I. Dworkin; Paleosol barometer indicates extreme fluctuations in atmospheric CO2 across the Cretaceous-Tertiary boundary. Geology 2002;; 30 (8): 703–706. doi: https://doi.org/10.1130/0091-7613(2002)030<0703:PBIEFI>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract We present an atmospheric pCO2 (p is partial pressure) curve showing extreme fluctuations for the interval between ca. 77 and 63 Ma in southern Alberta, Canada, using a paleosol barometer. Paleosol carbonate nodules (micrite) were collected from 40 Bk horizons among 6 stratigraphic sections for stable carbon isotope analysis. Based on results from the study area, declining atmospheric pCO2 from 1200 ppmV (V is volume) in the Campanian to 780 ppmV in the Maastrichtian correlates with Late Cretaceous climate cooling and falling sea level as documented in global records. The remarkable rise in atmospheric pCO2 near 65.5 Ma (1440 ppmV) correlates with volcanic activity associated with the Deccan Traps, rising sea level, and warmer global climates. The decline in atmospheric pCO2 (760 ppmV) at the Cretaceous-Tertiary boundary and subsequent sharp rise into the Danian (1000 ppmV) occurred during static terrestrial temperatures and sea level. This work provides compelling evidence that atmospheric pCO2 curves modeled for the Phanerozoic do not offer the resolution needed to understand environmental conditions during catastrophic events in Earth's history. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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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 | 0.002 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.041 | 0.007 |
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".