Association of anatase (TiO2) and microbes: unusual fossilization effect or a potential biosignature?

Geological Society of America Bulletin
By: , and 



We combined microbial paleontology and molecular biology methods to study the Eyreville B drill core from the 35.3-Ma-old Chesapeake Bay impact structure,Virginia, USA. The investigated sample is a pyrite vein collected from the 1353.81-1353.89 m depth interval, located within a section of biotite granite. The granite is a pre-impact rock that was disrupted by the impact event. A search for inorganic (mineral) biosignatures revealed the presence of micron-size rod morphologies of anatase (TiO2) embedded in chlorite coatings on pyrite grains. Neither the Acridine Orange microbial probe nor deoxyribonucleic acid (DNA) extraction followed by polymerase chain reaction (PCR) amplifi cation showed the presence of DNA or ribonucleic acid (RNA) at the location of anatase rods, implying the absence of viable cells in the investigated area. A Nile Red microbial probe revealed the presence of lipids in the rods. Because most of the lipids are resistant over geologic time spans, they are good biomarkers, and they are an indicator of biogenicity for these possibly 35-Ma-old microbial fossils. The mineral assemblage suggests that rod morphologies are associated with low-temperature (<100 °C) hydrothermal alteration that involved aqueous fl uids. The temporal constraints on the anatase fossils are still uncertain because pre-impact alteration of the granite and postimpact heating may have provided identical conditions for anatase precipitation and microbial preservation.

Publication type Article
Publication Subtype Journal Article
Title Association of anatase (TiO2) and microbes: unusual fossilization effect or a potential biosignature?
Series title Geological Society of America Bulletin
DOI 10.1130/2009.2458(42)
Volume 458
Year Published 2015
Language English
Publisher Geological Society of America
Publisher location Washington, D.C.
Contributing office(s) National Research Program - Eastern Branch
Description 11 p.
First page 965
Last page 975
Online Only (Y/N) N
Additional Online Files (Y/N) N
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