DOI: 10.1038/ngeo2025
论文题名: Evidence for biogenic graphite in early archaean isua metasedimentary rocks
作者: Ohtomo Y. ; Kakegawa T. ; Ishida A. ; Nagase T. ; Rosing M.T.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2014
卷: 7, 期: 1 起始页码: 25
结束页码: 28
语种: 英语
英文摘要: Some graphite contained in the 3.7-billion-year-old metasedimentary rocks of the Isua Supracrustal Belt, Western Greenland, is depleted in 13 C and has been interpreted as evidence for early life. However, it is unclear whether this graphite is primary, or was precipitated from metamorphic or igneous fluids. Here we analyse the geochemistry and structure of the 13 C-depleted graphite in the Isua schists. Raman spectroscopy and geochemical analyses indicate that the schists are formed from clastic marine sediments that contained 13 C-depleted carbon at the time of their deposition. Transmission electron microscope observations show that graphite in the schist occurs as nanoscale polygonal and tube-like grains, in contrast to abiotic graphite in carbonate veins that exhibits a flaky morphology. Furthermore, the graphite grains in the schist contain distorted crystal structures and disordered stacking of sheets of graphene. The observed morphologies are consistent with pyrolysation and pressurization of structurally heterogeneous organic compounds during metamorphism. We thus conclude that the graphite contained in the Isua metasediments represents traces of early life that flourished in the oceans at least 3.7 billion years ago. © 2014 Macmillan Publishers Limited. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106420
Appears in Collections: 气候减缓与适应 科学计划与规划
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作者单位: Tohoku University, Division of Earth and Planetary Materials Science, Graduate School of Science, 980-8578,Tohoku, Japan; Nordic Center for Earth Evolution, Natural History Museum of Denmark, University of Copenhagen, 1350 Copenhagen, Denmark
Recommended Citation:
Ohtomo Y.,Kakegawa T.,Ishida A.,et al. Evidence for biogenic graphite in early archaean isua metasedimentary rocks[J]. Nature Geoscience,2014-01-01,7(1)