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184 / 2025-04-14 11:45:56
Micro-boring chemolithotrophs in Paleoproterozoic hydrothermal hyaloclastites may have searched for phosphate nutrients
Micro-Raman, FIB-TEM, stable isotopes, correlated microscopy
Theme 1: Novel Tools and Techniques in Geobiology > Session 1b: Advances in Geobiology Catalysed by Correlated Microscopy at the Nanoscale
摘要待审
Dominic Papineau / Chinese Academy of Science; Institute of Deep-Sea Science and Engineering
Ichnofossils in basaltic glass are putative microscopic trace fossils and/or burrows that occur in hydrothermally influenced sea-floor environments, and they have been reported from throughout Earth history. However, their ecological role and the reason why microorganisms should make burrows in volcanic glass remains unknown. In this work, we use correlated microscopy to investigate the possible metabolisms of new ichnofossils documented from the ca. 1,870 Ma Flaherty Formation of the Belcher Group. The Flaherty Fm. consists in a succession of pillow basalt flows interbedded with hydrothermally altered seafloor sediments. Fossiliferous hyaloclastite occurs along strike and adjacent to meter-size pinnacle-shaped towers of accretionary lapilli in carbonatized and silicified basalt as well as isolated pods of gossan, indicating the past presence seafloor hydrothermal exhalations. Organic Carbon isotope values vary between -29 and -37 permil, carbonate carbon isotope values are between -1 and -11 permil, and sulphide sulphur isotope analyses range from +2 to +12 permil, collectively possibly consistent with a chemolithotrophic ecosystem with significant oxidation of organic matter. Polarising microscopy and micro-Raman imaging revealed trails of organic-rich coccoidal microfossils palagonitised to titanite co-occur with different types of indigenous organic matter that also forms very fine disseminations of apatite. Other candidate microfossils in these basaltic glass shards include tubes and different types of coccoids, similarly organic-rich and palagonitised to titanite. Correlated focused ion beam and transmission electron microscopy analyses show the nanoscopic size of apatite associated with organic matter in association with the purported microfossils. The new observations constitute evidence for Paleoproterozoic chemolithotrophy by microorganism that either dissolved the basaltic glass shards to concentrate P-nutrients for bioavailability, or that released organic acid and P during diagenetic decomposition leading to the precipitation of diagenetic apatite. Hence, chemolithotrophy was partly modulated by phosphate, and these microorganisms are interpreted to thrive in an oligotrophic microbial ecosystem in one of the oldest known shallow-marine, hydrothermal vent environments.
重要日期

  • 会议日期

    06月10日

    2025

    至

    06月13日

    2025

  • 04月15日 2025

    初稿截稿日期

主办单位
National Natural Science Foundation of China
Geobiology Society
National Committee of Stratigraphy of China
Ministry of Science and Technology
Geological Society of China
Paleontological Society of China
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (CAS)
Institute of Vertebrate Paleontology and Paleoanthropology, CAS
International Commission on Stratigraphy
International Paleontological Association
承办单位
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (CUG, Wuhan)
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