The role of seawater on the trace element geochemistry of some UK coals and a tribute to Goldschmidt

The Pennsylvanian coals in the UK were deposited in a low-lying delta plain which was periodically inundated by the sea. This resulted in high S contents, mainly due to early diagenetic pyrite. Based on a statistical analysis of the geochemical data, pyrite is the major host for As, Se, Hg, Tl and Pb and an important host for Mo, Cd, Ni, Sb and Cu. All of these elements are enriched in the coals compared with non-marine mudrocks in the sequence, as is Ge and Be, although theirs is an organic association. The pattern of enrichment in the coals is similar to that in marine shales and coals overlain by marine shales, demonstrating the seawater influence. Goldschmidt was a pioneer in the geochemical study of coals and this paper will demonstrate that many of his ideas have stood the test of time.