From the abstract of the paper: https://link.springer.com/article/10.1007%2Fs12520-018-0599-5 https://link.springer.com/article/10.1007%2Fs12520-018-0599-...

From the abstract of the paper: https://link.springer.com/article/10.1007%2Fs12520-018-0599-5 https://link.springer.com/article/10.1007%2Fs12520-018-0599-... "Two thousand years ago, only supernatural forces could explain these phenomena from Hadean depths whereas nowadays, modern techniques hint to the well-known phenomenon of geogenic CO2 degassing having mantle components with relatively higher helium and radon concentrations."