scholarly journals Reconciling proxy records and models of Earth's oxygenation during the Neoproterozoic and Palaeozoic

2020 ◽  
Vol 10 (4) ◽  
pp. 20190137 ◽  
Author(s):  
Rosalie Tostevin ◽  
Benjamin J. W. Mills
Keyword(s):  
Continuous Model ◽  
Biogeochemical Model ◽  
Animal Life ◽  
Oxygen Levels ◽  
Earth’S Atmosphere ◽  
The Past ◽  
Proxy Records ◽  
Late Palaeozoic ◽  
Earth's Atmosphere ◽  
Early Palaeozoic

A hypothesized rise in oxygen levels in the Neoproterozoic, dubbed the Neoproterozoic Oxygenation Event, has been repeatedly linked to the origin and rise of animal life. However, a new body of work has emerged over the past decade that questions this narrative. We explore available proxy records of atmospheric and marine oxygenation and, considering the unique systematics of each geochemical system, attempt to reconcile the data. We also present new results from a comprehensive COPSE biogeochemical model that combines several recent additions, to create a continuous model record from 850 to 250 Ma. We conclude that oxygen levels were intermediate across the Ediacaran and early Palaeozoic, and highly dynamic. Stable, modern-like conditions were not reached until the Late Palaeozoic. We therefore propose that the terms Neoproterozoic Oxygenation Window and Palaeozoic Oxygenation Event are more appropriate descriptors of the rise of oxygen in Earth's atmosphere and oceans.

scholarly journals The Escape of Planetary Atmospheres

1974 ◽  
Vol 65 ◽  
pp. 37-39 ◽  
Author(s):  
Donald H. Menzel
Keyword(s):  
Planetary Atmospheres ◽  
Second Century ◽  
The Moon ◽  
Ancient History ◽  
Earth’S Atmosphere ◽  
The Past ◽  
The Earth ◽  
Earth's Atmosphere

The problem of escape of atmospheres from the Moon and planets has roots deep in ancient history. Many of the great philosophers of the past regarded the Earth's atmosphere as a medium extending to infinity, with a stationary Earth imbedded at the center. Indeed, it was this concept that led Ptolemy, among many others, to conclude that the Earth could not be moving, for otherwise it would be subject to a gale-force wind caused by its own motion. This idea fostered many of the early stories of interplanetary visitations. Lucian, for example, writing in the second century A.D., has his Icarome nippus fly to the Moon and beyond by means of wings attached to his body.

scholarly journals Experimental and Theoretical Data on Radiocarbon Variation in the Earth's Atmosphere in the Past

Radiocarbon ◽  
1980 ◽  
Vol 22 (2) ◽  
pp. 328-336 ◽  
Author(s):  
V A Dergachev
Keyword(s):  
Solar Activity ◽  
Theoretical Data ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Earth’S Atmosphere ◽  
The Past ◽  
Earth's Atmosphere

Some questions in the study of cosmic ray intensity (solar magnetic irregular solar activity, 14CO2, and 14CO in radiocarbon models, etc) on the basis of 14C concentration in the earth's atmosphere are considered.

scholarly journals Widespread hematite at high latitudes of the Moon

2020 ◽  
Vol 6 (36) ◽  
pp. eaba1940 ◽  
Author(s):  
Shuai Li ◽  
Paul G. Lucey ◽  
Abigail A. Fraeman ◽  
Andrew R. Poppe ◽  
Vivian Z. Sun ◽  
...  
Keyword(s):  
Ferric Iron ◽  
High Latitudes ◽  
The Moon ◽  
Earth’S Atmosphere ◽  
The Past ◽  
Reducing Conditions ◽  
Moon Mineralogy Mapper ◽  
Earth's Atmosphere ◽  
Iron Bearing ◽  
Isotope Measurements

Hematite (Fe2O3) is a common oxidization product on Earth, Mars, and some asteroids. Although oxidizing processes have been speculated to operate on the lunar surface and form ferric iron–bearing minerals, unambiguous detections of ferric minerals forming under highly reducing conditions on the Moon have remained elusive. Our analyses of the Moon Mineralogy Mapper data show that hematite, a ferric mineral, is present at high latitudes on the Moon, mostly associated with east- and equator-facing sides of topographic highs, and is more prevalent on the nearside than the farside. Oxygen delivered from Earth’s upper atmosphere could be the major oxidant that forms lunar hematite. Hematite at craters of different ages may have preserved the oxygen isotopes of Earth’s atmosphere in the past billions of years. Future oxygen isotope measurements can test our hypothesis and may help reveal the evolution of Earth’s atmosphere.

scholarly journals Did Bacterial Enzymes Cap the Oxygen in Early Earth’s Atmosphere?

Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
Sarah Derouin
Keyword(s):  
Bacterial Enzymes ◽  
Oxygen Levels ◽  
Earth’S Atmosphere ◽  
Great Oxidation Event ◽  
Earth's Atmosphere

A new theory suggests that nitrogenase from cyanobacteria could be the reason oxygen levels remained low after the Great Oxidation Event.

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