The nucleogenic isotopes36Cl,236U and239Pu are produced naturally in subsurface environments via neutron capture of thermal and epithermal neutrons. Concentrations are, however, very low and accelerator mass spectrometry (AMS) is required for quantitative measurements. A particular challenge is presented by the measurement of236U/238U ratios down to the level of 10-13that is expected from rocks with low uranium concentration. Here, we present the AMS methodology that has been developed at the ANU for measuring236U/238U ratios at this level. The more established methodologies for36Cl and239Pu measurements are also summarised. These capabilities are then used to characterize the36Cl,236U and239Pu concentrations in a range of uranium ores. A simple model of the neutron production and capture processes in subsurface environments has been developed and is presented. It is shown that nucleogenic36Cl,236U and239Pu can be used to determine both thermal and epithermal neutron fluxes in subsurface environments. Potential applications include uranium exploration and monitoring of the environmental impact of uranium mining. © 2008 Elsevier B.V. All rights reserved.