TY - JOUR

T1 - Petrographic carbon in ancient sediments constrains Proterozoic Era atmospheric oxygen levels

AU - Canfield, Don E.

AU - van Zuilen, Mark A.

AU - Nabhan, Sami

AU - Bjerrum, Christian J.

AU - Zhang, Shuichang

AU - Wang, Huajian

AU - Wang, Xiaomei

PY - 2021

Y1 - 2021

N2 - Oxygen concentration defines the chemical structure of Earth's ecosystems while it also fuels the metabolism of aerobic organisms. As different aerobes have different oxygen requirements, the evolution of oxygen levels through time has likely impacted both environmental chemistry and the history of life. Understanding the relationship between atmospheric oxygen levels, the chemical environment, and life, however, is hampered by uncertainties in the history of oxygen levels. We report over 5,700 Raman analyses of organic matter from nine geological formations spanning in time from 742 to 1,729 Ma. We find that organic matter was effectively oxidized during weathering and little was recycled into marine sediments. Indeed, during this time interval, organic matter was as efficiently oxidized during weathering as it is now. From these observations, we constrain minimum atmospheric oxygen levels to between 2 to 24% of present levels from the late Paleoproterozoic Era into the Neoproterozoic Era. Indeed, our results reveal that eukaryote evolution, including early animal evolution, was not likely hindered by oxygen through this time interval. Our results also show that due to efficient organic recycling during weathering, carbon cycle dynamics can be assessed directly from the sediment carbon record.

AB - Oxygen concentration defines the chemical structure of Earth's ecosystems while it also fuels the metabolism of aerobic organisms. As different aerobes have different oxygen requirements, the evolution of oxygen levels through time has likely impacted both environmental chemistry and the history of life. Understanding the relationship between atmospheric oxygen levels, the chemical environment, and life, however, is hampered by uncertainties in the history of oxygen levels. We report over 5,700 Raman analyses of organic matter from nine geological formations spanning in time from 742 to 1,729 Ma. We find that organic matter was effectively oxidized during weathering and little was recycled into marine sediments. Indeed, during this time interval, organic matter was as efficiently oxidized during weathering as it is now. From these observations, we constrain minimum atmospheric oxygen levels to between 2 to 24% of present levels from the late Paleoproterozoic Era into the Neoproterozoic Era. Indeed, our results reveal that eukaryote evolution, including early animal evolution, was not likely hindered by oxygen through this time interval. Our results also show that due to efficient organic recycling during weathering, carbon cycle dynamics can be assessed directly from the sediment carbon record.

KW - oxygen

KW - Proterozoic

KW - evolution

KW - weathering

KW - graphite

KW - GRAPHITIC BLACK CARBON

KW - ORGANIC-CARBON

KW - EVOLUTION

KW - OXIDATION

KW - GAS

KW - METASEDIMENTS

KW - RESPIRATION

KW - DEGRADATION

KW - MATTER

KW - RECORD

U2 - 10.1073/pnas.2101544118

DO - 10.1073/pnas.2101544118

M3 - Journal article

C2 - 34074783

VL - 118

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 23

M1 - 2101544118

ER -