『Abstract
　Alteration textures in volcanic glass from the seafloor fall into two classes, one suggestive of abiotic/diffusive hydration and chemical exchange, and another likely to be caused by microbial, cavity-forming, congruent dissolution. Glass bioalteration is common in submarine lavas throughout the world's ocean, dominant in the upper 300 m of the oceanic crust, and found in all well-preserved ophiolites and greenstone belts dating back to 3.5 Ga. It may yield a significant fraction of the global biomass and geochemical fluxes and is relevant to the development of the earliest life on Earth. We present a critical review concerning these glass bioalteration textures and present new data on their microchemical environment. We explore arguments for their biogenicity and further develop the prevalent model for their formation by relating corrosion morphology to the mechanism of microbial dissolution. Biological alteration produces conspicuous micron-scale granular and tubular textures. Granular glass alteration is well explained by colonizing microbes that selectively dissolve the glass in their contact area, forming a sponge-like interconnected network of micron-sized cavities along glass surfaces. Tubular alteration meanwhile, is more likely to be caused by filamentous cell extensions in a process similar to fungal tunneling of soil feldspars and marine carbonates. while we see clear functional similarities to fungal dissolution behavior, we do not know whether fungal or prokaryotic organisms are involved. However, this functional constraint may eventually help to identify potential microbes responsible for these features, potentially including eukaryotic or prokaryotic organisms. Yet, we caution that these organisms my be difficult to identify and to study, because they are likely to be sparsely distributed, slow growing, and difficult to cultivate.

Keywords: volcanic glass; microbes; bioerosion; oceanic crust; ophiolites; greenstone belts』

Constants
1. Introduction
2. Bioalteration textures in volcanic glass
　2.1. Abiotic glass alteration
　2.2. Biotic alteration textures
3. Bioalteration textures in feldspars and carbonates
4. Occurrence, geological and environmental context and age of glass bioalteration
　4.1. Occurrence
　4.2. Geological context
　4.3. Antiquity and duration of bioalteration
5. Geochemistry of glass bioalteration
　5.1. The geochemical environment of glass bioalteration
　5.2. Fingerprinting volcanic glass bioalteration
　5.3. Chemical mobility and fractionation during bioalteration of glass
6. Microbiology of volcanic glass alteration
7. Discussion
　7.1. Biogenicity
　7.2. A model for microbial alteration of volcanic glass
　7.3. Relevance of bioalteration
　7.4. Early life and the evolution of glass bioalteration
Acknowledgements
References