Sedimentological Evolution and Sedimentological Evolution and Natural Radioactivity of Tertiary Sediments From the Central North Sea

In the North Sea well studied in this paper, the radioactive isotopes of U, Th and K are shown to control the variations in the gamma‐log response. Th and K are associated with the clay fraction, while U is enriched in the silt fraction. In the volcaniclastic Palaeocene and Eocene beds, low gamma activity is due to a high content of volcanic debris poor in U and Th, while higher gamma activity in the younger beds indicates the decrease in volcaniclastic material.