Biological role in geyserite formation

Characterize the degree and nature of biological involvement in the formation of geyserites (opal-A silica deposits near geysers), distinguishing abiogenic precipitation from microbially mediated nucleation and templating, and define criteria for recognizing biogenic contributions in ancient geyserites.

Background

Geyserites are silica-rich sinters with distinctive microtextures formed in high-temperature hydrothermal settings. Some studies attribute their formation to abiotic processes, while others document microbial templating and silicification.

The review notes that the extent and consistency of biological influence across settings and through time is unresolved, with implications for interpreting silica sinter textures as biosignatures.