Experimental abiotic alteration of igneous and manufactured glasses

This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/journals/comptes-rendus-geoscience/1631-0713.Microchannels in ocean basalt glass are often attributed to the activity of microorganisms, however, neither the mechanism of formation of microchannels in glass nor the involvement of microorganisms have been confirmed by experimentation. Experimental abiotic corrosion of basalt glass with 1% hydrofluoric acid (HF), a proxy for more slowly acting organic or inorganic acids, produces pits that are similar in size, shape, and distribution to pits found in basalt glass collected from the ocean floor and basalt glass incubated with microorganism. This pit formation was demonstrated by comparing secondary electron images taken before and after the acid treatment. In one sample, 1-μm-diameter pits produced by HF corrosion of basalt glass coalesced into larger pits that are similar to microchannels found in natural basalt glass. The formation of pits and microchannels by abiotic corrosion of basalt glass is an alternate hypothesis for the origin of these features, and the interpretation of these features as biomarkers may require a resolution of these alternative hypotheses