Ancient Oxygen Levels of Paleozoic Fluid Inclusions
Bibliographic record
Abstract
The Paleozoic (500-300 million years) was a dynamic era in Earth’s history characterized by environmental diversity and multiple extinction events. Understanding climate change throughout the Paleozoic not only allows for paleoclimate reconstruction but offers a glimpse into how life has progressed through time. By studying oxygen, one of the most important facets of any climate, the fluctuation of oxygen and its link to rises and declines of life throughout the Paleozoic may be studied. Halite offers a unique approach to studying the facets of Earth’s past temperatures due to its ability to form fluid inclusions, which can be studied using microthermometry to measure actual formation temperatures during halite crystallization at the brine-surface interface. This study aims to utilize halite-hosted fluid inclusions that contain trapped air bubbles to determine the atmospheric concentration of oxygen and Paleozoic temperatures at which the halite precipitated, as well as chemical characteristics in each area that the halite precipitated. This study utilizes multiple methodologies, including cutting-edge gas analysis to directly measure the atmospheric gases trapped in fluid inclusions, microthermometry and trace chemistry. Using halite dated to the Cambrian, Silurian and Permian from various areas, respectively Australia, Canada and the United States allows for a detailed understanding of their environmental conditions during halite crystallization, by determining surface atmospheric air composition, temperature at halite formation and trace chemical characteristics of the halite and surrounding strata. Atmospheric oxygen concentrations ranged throughout the Paleozoic and changed when approaching or following extinction events. In the late Cambrian, O2 levels were around 11.60% (± 1.04). In the Silurian, an environmentally stable period, O2 increased to 16.23% (± 1.04), closer to modern atmospheric levels of ~ 21%. The Permian, a period of extinction events, saw the beginning of a decrease in O2 content, from 16.05% (± 1.04) in the Leonardian stage (280 Ma), before dropping to 10.08% (± 1.04) O2 in the Guadalupian stage (260 Ma) as the end-Guadalupian extinction occurred. These results provide insight on the fluctuations of both surface temperatures and atmospheric oxygen levels.
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".