Exposed Al foil for carbon leader sample (E5-46/48-HS4-I) that has been innoculated with 35SO4 and incubated at 60°C(?) using the procedure of Krumholz et al. (1998). Activity is concentrated along the organic rich layer sandwich between the quartz pebbles of the carbon leader. Although tracer data indicates this sample may be contaminated, it remains to be seen whether this activity reflects that of contaminant microorganisms. Another carbon leader sample (E5-46/48-HS3-I) and quartzite (E5-46/48-HS2I) barely yielded detectable signal.

References:

Krumholz, L.R., McKinley, J.P., Ulrich, G.A. and Suflita, J.M. (1997) Confined subsurface microbial communities in
    Cretaceous rock. Nature 386:64-66.