Radioactive fossils: The uranium anomaly and its paleobiological implications

In this study, several natural radionuclides (40K, 238U, 235U, 228Ac) and their decay product were investigated in various invertebrate and vertebrate fossils. In the high radioactivity group of fossils, 238U and 235U concentrations increased from 141 to 3621 Bq/kg and from 5.4 to 167 Bq/kg, respectively. In the low radioactivity group of fossils, concentrations of both U isotopes increased from 4.6 to 51 Bq/kg and from 0.18 to 2.3 Bq/kg, respectively. High radioactivity has been linked to the phosphatization process that affected the uranium sorption. Scanning of electron microscope images and X-ray fluorescence analysis were used to confirm the mode of preservation of studied fossils and the presence of a correlation between the phosphorus content and uranium elements in fossil specimens.

Automated summary

The study examined different natural radionuclides in invertebrate and vertebrate fossils and found higher concentrations of 238U and 235U in fossils with high radioactivity due to the phosphatization process. In fossils with low radioactivity, concentrations of both U isotopes also increased. Scanning electron microscope images and X-ray fluorescence analysis confirmed the preservation mode of fossils and the correlation between phosphorus content and uranium elements.