| Author(s): | Pedersen, K., Ekendahl, S., Tullborg, E-L., Furnes, H., Thorseth, I., Tumyr, O. |
| Year: | 1997 |
| Title: | Evidence of ancient life at 207 m depth in a granitic aquifer |
| Reference: | Geology |
| Keywords: | calcite, bacteria, stable isotopes, pyrite, Aspo, Sweden, deep groundwater, |
| Overview: | Calcite preciptated in a water-conducting fracture in granitic host rock at Äspö Island(Sweden)was found, in parts, to be isotopically extremely light in δ13C, indicative of biological activity. Detailed scanning electron microscop[y identified fossil bacteria within the calcite. On the basis of stable isotope data and trace element analyses, the processes calcite is beleived to have grown under conditions ranging from marine brackish to meteroric, possibly with a component of glacial meltwater, and at least some of the calcite is close to isotopic equilibrium with present-day groundwater. The results indicate that microbial activity has influenced the fracture mineralisation and the geochemical processes in deep groundwater systems in the past. |