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GEOPHYSICAL RESEARCH LETTERS,
VOL. 31,
L05202,
doi:10.1029/2003GL018802,
2004
Biotic enhancement of weathering, atmospheric oxygen and carbon dioxide in the Neoproterozoic
Timothy M. Lenton
Centre for Ecology and Hydrology, Bush Estate, Penicuik, UK
Andrew J. Watson
School of Environmental Sciences, University of East Anglia, Norwich, UK
Abstract
It has been suggested that biological colonization of the land surface began in the Neoproterozoic 1000–544 million years
ago (Ma). We hypothesize that this colonization involved selective weathering of P from rocks, as well as an amplification
of overall weathering rates. We show that two recent models, despite differences in the feedback mechanisms represented, predict
that an increase in the weathering flux of P to the ocean would have caused a rise in atmospheric O2 in the Neoproterozoic. This in turn may have provided a necessary condition for the evolution of animals with hard skeletons
seen in the ‘Cambrian explosion’. Increased weathering of silicate rocks would also have caused a decline in atmospheric CO2, which could have been a causal factor in the Neoproterozoic glaciations.
Received 9
October
2003;
accepted 10
February
2004;
published 10
March
2004.
Index Terms: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0330 Atmospheric Composition and Structure: Geochemical cycles; 1886 Hydrology: Weathering (1625); 4805 Oceanography: Biological and Chemical: Biogeochemical cycles (1615); 9619 Information Related to Geologic Time: Precambrian.
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Citation: Lenton, T. M., and A. J. Watson
(2004),
Biotic enhancement of weathering, atmospheric oxygen and carbon dioxide in the Neoproterozoic,
Geophys. Res. Lett.,
31,
L05202,
doi:10.1029/2003GL018802.
Copyright 2004 by the American Geophysical Union.
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