Oil shale geology is a branch of geologic sciences which studies the formation and composition of oil shales–fine-grained sedimentary rocks containing significant amounts of kerogen, and belonging to the group of sapropel fuels.[1] Oil shale formation takes place in a number of depositional settings and has considerable compositional variation. Oil shales can be classified by their composition (carbonate minerals such as calcite or detrital minerals such as quartz and clays) or by their depositional environment (large lakes, shallow marine, and lagoon/small lake settings). Much of the organic matter in oil shale is of algal origin, but may also include remains of vascular land plants. Three major type of organic matter (macerals) in oil shale are telalginite, lamalginite, and bituminite.[2] Some oil-shale deposits also contain metals which include vanadium, zinc, copper, uranium.[1][3]

https://en.wikipedia.org/wiki/Oil_shale_geology

Mrs/Miss/Mr. De,

The organic matter is the major factor governing the migration of Ans/Lns, including towards their adsorption ability toward the inorganic matter. The latter process, as is well known, is accepted as the leading interacting process of Ans/Lns in the environment.

Dear Mrs/Mr. De,

Your questions are strongly differing from each other although they have one thing in common, organic matter.

As to your question 1:

There are sapropelitic shales or black shales reflecting a fully euxinic redox regime, the equivalent sediments with a lesser reducing regime may be called gyttia or grey shales.

As to your question 2:

There is a link between organic rich shales and U, because tetravalent U becomes fixed, whereas under more oxidizing conditions U in its hexavalent state is very mobile. U deposits are encountered in the black shales. Due to the high U content, these black shales are also called "hot shales" . High gamma read-outs in wireline logs as such stand for euxinic conditions, high U contents and high TOC (total organic carbon). There is a direct correlation between these chemical and radio-physical components. Please take care. You do not measure U but U equivalents re-calculated from Bi-214. Uranium U-238 emits alpha ray mainly. Thorium is rather immobile, exists only in its tetravalent state and does not respond to these redox changes and is normally transported in heavy minerals such as xenotime, zircon or monazite which do not come to rest in argillaceous but arenaceous sediments

In the attached file the chemical changes are illustrated for black and gray shales being enriched in U.

Best regards

H.G.Dill