The Radioactive Content of the Coal Measures Sediments in the Yorkshire–derbyshire Coalfield

Summary Measurements of the radioactivity of a large number of samples of marine and non-marine sediments in the Yorkshire-Derbyshire coalfield have been made and the results analysed statistically. Phosphate, carbonaceous and potassium contents have been determined and the relationship between these and the radioactivity examined. Alpha track data were obtained by autoradiography. The results show that of the marine bands only the Alton and the Mansfield are consistently and markedly radioactive. The high levels of radioactivity are commonly associated with phosphate in the form of collophane and with certain types of carbonaceous and bituminous matter. For the Alton Marine Band in particular there are close correlations between these constituents and the beta-radioactivity. The conditions of deposition of the highly radioactive marine sediments are discussed. In the sediments where the radioactivity is low, the isotope K 40 is the most important source of beta-radioactivity. The low uranium-thorium content is mainly disseminated through the fine-grained constituents and there are only rare occurrences of highly radioactive constituents in the form of organic matter or zircon.