Researchers compiled previously published thorium-uranium ratios (Th/U) of more than 29,000 igneous rocks spanning the past 3 billion years and report 2 dramatic decreases occurring at approximately 2.35 and 0.75 billion years ago, consistent with previously established dates for the Great Oxidation and Neoproterozoic Oxygenation Events, respectively, the two main stages in the rise of atmospheric oxygen, suggesting that Th/U might be an effective record of atmospheric oxygen levels.
Article #19-02833: "Global atmospheric oxygen variations recorded by Th/U systematics of igneous rocks," by He Liu, Robert E. Zartman, Trevor R. Ireland, and Weidong Sun.
MEDIA CONTACT: Weidong Sun, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, CHINA; e-mail: weidongsun@gig.ac.cn ; He Liu, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, CHINA; tel: +86-13810261865; e-mail: liuhe@qdio.ac.cn
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Proceedings of the National Academy of Sciences