Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments
Fluviolacustrine sediments of the 2.75 Ga Hardey Formation (Fortescue Group, Australia) preserve pendant columnar structures with stromatolitic lamination within synsedimentary cavities. The millimeter-sized, finger-like columns strongly resemble microbialites from modern basaltic caves and indicate...
| Main Authors: | , , , |
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| Format: | Journal Article |
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Geological Society of America Inc
2009
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| Online Access: | http://hdl.handle.net/20.500.11937/31174 |
| _version_ | 1848753303479910400 |
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| author | Rasmussen, Birger Blake, T. Fletcher, Ian Kilburn, M. |
| author_facet | Rasmussen, Birger Blake, T. Fletcher, Ian Kilburn, M. |
| author_sort | Rasmussen, Birger |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Fluviolacustrine sediments of the 2.75 Ga Hardey Formation (Fortescue Group, Australia) preserve pendant columnar structures with stromatolitic lamination within synsedimentary cavities. The millimeter-sized, finger-like columns strongly resemble microbialites from modern basaltic caves and indicate the likely presence of microbial biofi lms. The ancient microbial columns are preserved by chert and locally occur as reworked clasts, indicating a near-depositional age for the structures. Sulfur isotopic analysis of pyrite in the columns and adjacent carbonaceous matrix yields d34SCDT (CDT?Canyon Diablo troilite) values between -8.5? and +19?, showing signifi cant fractionation characteristic of biological cycling of sulfur. Organic matter in cavity ceilings and shale matrix has d13CPDB (PDB?Peedee belemnite) values between -55? and -43?, suggesting the presence of methanotrophs. Our results suggest that 2.75 Ga terrestrial environments supported a microbial ecosystem, including microbes that inhabited synsedimentary hollows, extending the fossil record of coelobionts by ~1.5 b.y. Subsurface cavities represent a new habitable microenvironment for early life on Earth, and an analogue for ancient life on Mars. |
| first_indexed | 2025-11-14T08:22:22Z |
| format | Journal Article |
| id | curtin-20.500.11937-31174 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:22:22Z |
| publishDate | 2009 |
| publisher | Geological Society of America Inc |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-311742017-09-13T15:55:20Z Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments Rasmussen, Birger Blake, T. Fletcher, Ian Kilburn, M. synsedimentary cavities methanotrophs coelobionts Hardey Formation microbial columns Fluviolacustrine sediments of the 2.75 Ga Hardey Formation (Fortescue Group, Australia) preserve pendant columnar structures with stromatolitic lamination within synsedimentary cavities. The millimeter-sized, finger-like columns strongly resemble microbialites from modern basaltic caves and indicate the likely presence of microbial biofi lms. The ancient microbial columns are preserved by chert and locally occur as reworked clasts, indicating a near-depositional age for the structures. Sulfur isotopic analysis of pyrite in the columns and adjacent carbonaceous matrix yields d34SCDT (CDT?Canyon Diablo troilite) values between -8.5? and +19?, showing signifi cant fractionation characteristic of biological cycling of sulfur. Organic matter in cavity ceilings and shale matrix has d13CPDB (PDB?Peedee belemnite) values between -55? and -43?, suggesting the presence of methanotrophs. Our results suggest that 2.75 Ga terrestrial environments supported a microbial ecosystem, including microbes that inhabited synsedimentary hollows, extending the fossil record of coelobionts by ~1.5 b.y. Subsurface cavities represent a new habitable microenvironment for early life on Earth, and an analogue for ancient life on Mars. 2009 Journal Article http://hdl.handle.net/20.500.11937/31174 10.1130/G25300A.1 Geological Society of America Inc restricted |
| spellingShingle | synsedimentary cavities methanotrophs coelobionts Hardey Formation microbial columns Rasmussen, Birger Blake, T. Fletcher, Ian Kilburn, M. Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments |
| title | Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments |
| title_full | Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments |
| title_fullStr | Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments |
| title_full_unstemmed | Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments |
| title_short | Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments |
| title_sort | evidence for microbial life in synsedimentary cavities from 2.75 ga terrestrial environments |
| topic | synsedimentary cavities methanotrophs coelobionts Hardey Formation microbial columns |
| url | http://hdl.handle.net/20.500.11937/31174 |