Large negative excursion of organic carbon isotope in the aftermath of the Paleoproterozoic glaciation in North America: methane-hydrate destabilization, climate recovery, and the Great Oxidation Event

HR: 1340h
AN: PP43B-1244 [Abstracts]
TI: Large negative excursion of organic carbon isotope in the aftermath of the Paleoproterozoic glaciation in North America: methane-hydrate destabilization, climate recovery, and the Great Oxidation Event
AU: * Sekine, Y
EM: sekine@impact.k.u-tokyo.ac.jp
AF: Dept of Complexity Sci & Engr, Graduate School of Frontier Sci, Univ. of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8562, Japan
AU: Tajika, E
EM: tajika@eps.s.u-tokyo.ac.jp
AF: Dept of Earth & Planetary Sci, Graduate School of Sci, Univ. of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 111-0032, Japan
AU: Ohkouchi, N
EM: nohkouchi@jamstec.go.jp
AF: Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Sci & Tech, 2-15 Natsushima, Yokosuka, 237-0061, Japan
AU: Ogawa, N O
EM: nanaogawa@jamstec.go.jp
AF: Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Sci & Tech, 2-15 Natsushima, Yokosuka, 237-0061, Japan
AU: Goto, K
EM: kgoto@tsunami2.civil.tohoku.ac.jp
AF: Disaster Control Research Center, Graduate School of Engineering, Tohoku Univ., Aoba 06, Sendai, 980-8579, Japan
AU: Tada, R
EM: ryuji@eps.s.u-tokyo.ac.jp
AF: Dept of Earth & Planetary Sci, Graduate School of Sci, Univ. of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 111-0032, Japan
AU: Kanai, K
EM: ken_kanai77@yahoo.co.jp
AF: Dept of Earth & Planetary Sci, Graduate School of Sci, Univ. of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 111-0032, Japan
AU: Yamamoto, S
EM: yamashin.osachi@mx7.ttcn.ne.jp
AF: Dept of Earth & Planetary Sci, Graduate School of Sci, Univ. of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 111-0032, Japan
AB: The early Paleoproterozoic era (2.5 to 2.0 Ga) is a key interval in the Earth history characterized by glacial epoch and the rise of oxygen in the atmosphere. In 2.45 to 2.2 Ga, the Earth had been experienced a number of glaciations, at least one of which may have been a low-latitude glaciation. Following the glacial epoch, large positive excursions of carbon isotopic composition of carbonate are recorded in the sedimentary rocks of 2.2 to 2.0 Ga, suggesting anomalously high burial rates of organic carbon and thus massive release of oxygen to the atmosphere (called the “Great Oxidation Event”). Although climatic recovery in the aftermath of the glaciation is a key to understand the linkage between these two global events, the mechanism responsible for the environmental change has been largely unknown. Here we report large negative excursions of carbon isotopic composition of organic carbon (-45 to -60 permillage) from quartzites bracketed between the youngest Paleoproterozoic glacial diamictites and the carbonates recording the onset of the Great Oxidation Event both in the Chocolay Group of the Marquette Range Supergroup, USA, and in the Huronian Supergroup, Canada. Anomalous negative excursion of organic carbon isotope in deeply weathered quartzites suggests destabilization of methane hydrate as much as 50 to 150 percent of the modern hydrate pool. This may have resulted in an extreme greenhouse condition, which would have produced deeply weathered quartzites and supplied a large amount of nutrients to the oceans, resulting in the Great Oxidation Event.
DE: 1600 GLOBAL CHANGE
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 4901 Abrupt/rapid climate change (1605)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting