Page "Kerogen" Paragraph 3

The formation of geopolymers in this way accounts for the large molecular weights and diverse chemical compositions associated with kerogen.

The smallest geopolymers are the fulvic acids, the medium geopolymers are the humic, and the largest geopolymers are the humins.

When organic matter is contemporaneously deposited with geologic material, subsequent sedimentation and progressive burial or overburden provide significant pressure and temperature gradient.

When geopolymers are subjected to sufficient geothermal pressures for sufficient geologic time, they begin to undergo certain peculiar changes to become kerogen.

Such changes are indicative of the maturity stage of a particular kerogen.

These changes include loss of hydrogen, oxygen, nitrogen, and sulfur, which leads to loss of other functional groups that further promote isomerization and aromatization which are associated with increasing depth or burial.

Aromatization then allows for neat molecular stacking in sheets, which in turn increases molecular density and vitrinite reflectance properties, as well as changes in spore coloration, characteristically from yellow to orange to brown to black with increasing depth.