title: Osmium evidence for synchronicity between a rise in atmospheric oxygen and Palaeoproterozoic deglaciation.
abstract: Early Palaeoproterozoic (2.5-2.0 billion years ago) was a critical phase in Earth's history, characterized by multiple severe glaciations and a rise in atmospheric O(2) (the Great Oxidation Event). Although glaciations occurred at the time of O(2) increase, the relationship between climatic and atmospheric transitions remains poorly understood. Here we report high concentrations of the redox-sensitive element Os with high initial (187)Os/(188)Os values in a sandstone-siltstone interval that spans the transition from glacial diamictite to overlying carbonate in the Huronian Supergroup, Canada. Together with the results of Re, Mo and S analyses of the sediments, we suggest that immediately after the second Palaeoproterozoic glaciation, atmospheric O(2) levels became sufficiently high to deliver radiogenic continental Os to shallow-marine environments, indicating the synchronicity of an episode of increasing O(2) and deglaciation. This result supports the hypothesis that climatic recovery from the glaciations acted to accelerate the Great Oxidation Event.
authors: Department of Complexity Sci. & Engr., University of Tokyo, Kashiwanoha, Kashiwa, Chiba, Japan. sekine@k.u-tokyo.ac.jp
authors: Yasuhito
authors: Y
authors: Sekine
authors: Katsuhiko
authors: K
authors: Suzuki
authors: Ryoko
authors: R
authors: Senda
authors: Kosuke T
authors: KT
authors: Goto
authors: Eiichi
authors: E
authors: Tajika
authors: Ryuji
authors: R
authors: Tada
authors: Kazuhisa
authors: K
authors: Goto
authors: Shinji
authors: S
authors: Yamamoto
authors: Naohiko
authors: N
authors: Ohkouchi
authors: Nanako O
authors: NO
authors: Ogawa
authors: Teruyuki
authors: T
authors: Maruoka