Geochemical characteristics of rare earth elements in I/S clay rocks in Late-Pateozoic coal measures of Northern China

The clay rock samples from the Late-Paleozoic coalfields of Northern China are studied with ICP and INAA methods.The disordered I/S clay rock is characterized by lower REE contents and the middle to weak positive anomaly of Eu,but the ordered one is of higher REE contents and the strong to middle negative anomaly of Eu.The clay rocks differ form NASC in the REE contents and characteristics.The results show that the disordered and ordered clay rocks are respectively formed by intermediate and acidic pyroclasts in the sedimentary basins.