Japan Geoscience Union Meeting 2014

Presentation information

Oral

Symbol B (Biogeosciences) » B-PT Paleontology

[B-PT23_30AM1] Decoding the history of Earth: From Hadean to Modern

Wed. Apr 30, 2014 9:00 AM - 10:45 AM 411 (4F)

Convener:*Tsuyoshi Komiya(Department of Earth Science & Astronomy Graduate School of Arts and Sciences The University of Tokyo), Yasuhiro Kato(Department of Systems Innovation, Graduate School of Engineering, University of Tokyo), Katsuhiko Suzuki(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Chair:Honami Sato(Graduate School of Earth and Planetary Sciences, Kyushu University)

10:30 AM - 10:45 AM

[BPT23-07] Oceanic oxidation mechanisms spanning the Snowball Earth and early animal diversification

*Kunio KAIHO1, Atena SHIZUYA1, Masahiro OBA1, Kenji YAMADA1, Minori KIKUCHI1, Naoto SENBA1, Zhong-qiang CHEN2, Jinnan TONG2, Satoshi TAKAHASHI3, Li TIAN2, Tsuyoshi KOMIYA3 (1.Tohoku University, 2.China University of Geosciences, 3.University of Tokyo)

Keywords:Ediacaran, Cryogenian, Neoproterozoic, oxygen, biomarkers

The late Neoproterozoic (780 million years ago (Ma)) to early Cambrian (520 Ma) interval witnessed the rise and evolution of early animals. Oceanic oxidation is believed to be crucial in driving the early animal evolution. However, the oxygenation mechanism in seas during this critical period remains unknown. Here we found (i) oceanic anoxia before and during the Marinoan global glaciation (MGG) (660-635 Ma), (ii) surface-water reoxidation immediately after the MGG (635 Ma), (iii) intermediate-water oxidation in the mid-Ediacaran (600 Ma), (iv) deep-water oxidation in late Ediacaran (580 Ma), (v) oceanic anoxia at the end of the Ediacaran (541 Ma), and (vi) reoxidation in the early Cambrian (535 Ma). Thus, a stepwise marine oxygenation took place from shallow to deep water through the Ediacaran epoch, and every major changes in oxygen levels coincided with an important revolutions of marine life, suggesting a coevolution of ocean chemistry and early animals occurred during this period.