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ARCHEAN URANIUM DEPOSITS AND THE ORIGIN OF LIFE
by
León Garzón

URANIUM, URANINITE AND URANIUM DEPOSITS

The U⁴⁺ radius is greater than the radii of the ions that form the silicate lattices. For this reason, when the magma crystallizes, the U⁴⁺ is concentrated in the remaining fluids.

Due to the scarcity of the free O₂, before 2Ga years ago, uraninite (UO₂) was chemically stable. So, the early uranium deposits were of the placer type, being located in the cratons. Afterwards, UO₂ was oxidized and mobilized: a great variety of uranium deposits was developed, spreading more widely than before.

The enrichment in its ²³⁵U isotope was greater in the past (11.3%, 3.5 Ga years ago) than nowadays (0.72%)

There was a gamma field. Its dose rate in the atmosphere was:


D(gamma) = 3 x 10³ C microrad x h^-1
C: UO₂ concentration in %

The largest ²²²Rn cocentrations are found in the air and/or water that fills the voids of the subsoil.
If this belong to an uranium deposits the ²²²Rn concentration will be still much greater.
For this reason we have proposed the above mentioned subsoil as the most suitable environment to achieve the abiotic syntesis (more details)