1. NASA Astrobiology Institute and Department of Geosciences, Pennsylvania State University, 535 Deike Building, University Park, Pennsylvania 16802, USA
2. School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia

Correspondence to: Lee R. Kump¹ Correspondence and requests for materials should be addressed to L.R.K. (Email: lkump@psu.edu).

Abstract

The hypothesis that the establishment of a permanently oxygenated atmosphere at the Archaean–Proterozoic transition (2.5 billion years ago) occurred when oxygen-producing cyanobacteria evolved¹ is contradicted by biomarker evidence for their presence in rocks 200 million years older². To sustain vanishingly low oxygen levels despite near-modern rates of oxygen production from 2.7–2.5 billion years ago thus requires that oxygen sinks must have been much larger than they are now. Here we propose that the rise of atmospheric oxygen occurred because the predominant sink for oxygen in the Archaean era—enhanced submarine volcanism—was abruptly and permanently diminished during the Archaean–Proterozoic transition. Observations^{3, 4, 5} are consistent with the corollary that subaerial volcanism only became widespread after a major tectonic episode of continental stabilization at the beginning of the Proterozoic. Submarine volcanoes are more reducing than subaerial volcanoes⁶, so a shift from predominantly submarine to a mix of subaerial and submarine volcanism more similar to that observed today would have reduced the overall sink for oxygen and led to the rise of atmospheric oxygen.

1. NASA Astrobiology Institute and Department of Geosciences, Pennsylvania State University, 535 Deike Building, University Park, Pennsylvania 16802, USA
2. School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia

Correspondence to: Lee R. Kump¹ Correspondence and requests for materials should be addressed to L.R.K. (Email: lkump@psu.edu).

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