Show simple item record

dc.contributor.authorRasmussen, Birger
dc.contributor.authorBlake, T.
dc.contributor.authorFletcher, Ian
dc.contributor.authorKilburn, M.
dc.identifier.citationRasmussen, Birger and Blake, T. and Fletcher, Ian and Kilburn, M. 2009. Evidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments. Geology 37 (5): pp. 423-426.

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.

dc.publisherGeological Society of America Inc
dc.subjectsynsedimentary cavities
dc.subjectHardey Formation
dc.subjectmicrobial columns
dc.titleEvidence for microbial life in synsedimentary cavities from 2.75 Ga terrestrial environments
dc.typeJournal Article
curtin.accessStatusFulltext not available
curtin.facultyDepartment of Applied Geology
curtin.facultyFaculty of Science and Engineering
curtin.facultyWA School of Mines

Files in this item


This item appears in the following Collection(s)

Show simple item record