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Detection of the deep biosphere in metamorphic rocks from the Chinese continental scientific drilling
Author(s) -
Dai Xin,
Wang Yuanliang,
Luo Liqiang,
Pfiffner Susan M.,
Li Guangyu,
Dong Zhiyang,
Xu Zhiqin,
Dong Hailiang,
Huang Li
Publication year - 2021
Publication title -
geobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.859
H-Index - 72
eISSN - 1472-4669
pISSN - 1472-4677
DOI - 10.1111/gbi.12430
Subject(s) - biosphere , geology , scientific drilling , metamorphic rock , earth science , drilling , convergent boundary , geochemistry , paleontology , ecology , oceanic crust , subduction , mechanical engineering , tectonics , engineering , biology
It is generally accepted that there is a vast, well‐populated biosphere in the subsurface, but the depth limit of the terrestrial biosphere has yet to be determined, largely because of the lack of access to the subsurface. Here as part of the Chinese Continental Scientific Drilling (CCSD) project in eastern China, we acquired continuous rock cores and endeavored to probe the depth limit of the biosphere and the depth‐dependent distribution of microorganisms at a geologically unique site, that is, a convergent plate boundary. Microbiological analyses of ultra‐high‐pressure metamorphic rock cores taken from the ground surface to 5,158‐meter reveal that microbial distribution was continuous up to a depth of ~4,850 m, where temperature was estimated to be ~137°C. The metabolic state of these organisms at such great depth remains to be determined. Microbial abundance, ranging from 10 3 to 10 8 cells/g, was also related to porosity, but not to the depth and rock composition. In addition, microbial diversity systematically decreased with depth. Our results support the notion that temperature is a key factor in determining the lower limit of the biosphere in the continental subsurface.