Atmospheric oxygen of the Paleozoic

The evolution of Earth's atmosphere is extreme importance to the lithosphere, hydrosphere and biosphere. This particularly true for role biosphere played in inceptual formation atmospheric oxygen, subsequently its potential higher life forms. Quantifying change oxygen with geologic time extremely challenging, redox sensitive isotope element models subject contradictory outcomes. Here, we present a new approach determining past atmospheres, by a) directly measuring (DM) amount trapped fluid-gas inclusions primary unaltered halite, b) using back-calculation method (BCM) applied halite fluid inclusion gas contents subjected post-depositional biogeochemical reactions calculate oxygen. On average (±standard error), content during latest Ediacaran was 17.4 ± 2.1% compiled from DM 1.3% BCM 17.3 2.9%. For earliest Cambrian 19.3 1.4% 18.8 1.5% 19.8 1.3%. mid late Ordovician relatively invariant 15.6 1.8% [15.4 (DM), 15.8 2.2% (BCM)], 16.2 1.2% [15.7 1.7% 16.6 0.7% respectively. stable levels continued into Silurian 15.9 1.1% (12.9 0.4 16.5%, DM; 14.3 1.7 BCM) except peak about 23.2 1.9% (21.6% DM, 24.7 3.7% BCM). Early Carboniferous returned lower at 15.3 0.7 15.7 1.0% (15.0%, 15.5 0.1% 9.4 3.9 Similarly, halites Permian similar 16.9% 14.5 2.6% (BCM). Indeed, our study suggests that constant most Paleozoic 16.5% (±0.6 SE, ±2.2 SD). puts proxy result odds values trends suggested COPSE, GEOCARBSULF AND GEOCARBSULFOR early continues discord GEOCARBULFOR Paleozoic.