EVIDENCE OF ANCIENT-LIFE AT 207 M DEPTH IN A GRANITIC AQUIFER

The results of electron-microscopy investigations of calcite precipita ted in a water-conducting fracture in a ca, 1800 Ma granitic rock from 207 m below sea level at the island of Aspo on the southeastern (Balt ic) coast of Sweden are compared with measurements of carbon, oxygen, and sulfur isotope composition of the calcite and embedded pyrite, Par ts of the calcite had extremely low delta(13)C values, indicative of b iological activity, and contained bacteria-like microfossils occurring in colonies and as typical biofilms, X-ray microanalysis demonstrated these fossils to be enriched in carbon, Our results provide evidence for ancient life in deep granitic rock aquifers and suggest that the m odern microbial life found there is intrinsic, Modeling historical and present geochemical processes in deep granitic aquifers should, there fore, preferably include biologically catalyzed reactions, The results also suggest that the search for life on other planets, e.g., Mars, s hould include subsurface material.