CHEMICAL-STRUCTURE OF MIGRABITUMENS FROM SILURINA CRINOIDEA, PRAGUE BASIN, BARRANDIAN (BOHEMIA)

The chemical structure of migrabitumens (epi-impsonite, glance pitch, grahamite, ozocerite and weathered impsonite) from the Crinoidea genus Scyphocrinites, from the Silurian of the Prague Basin, Barrandian (Bo hemia) has been studied by diffuse reflectance infrared Fourier transf orm spectroscopy and solid state nuclear magnetic resonance. Oxidation of the samples in air at 150-degrees-C has been carried out in order to model structural changes of migrabitumens during weathering. We sug gest that the structural differences (H/C atomic ratios, content of ox ygen groups, aromaticities) between the migrabitumens of the same pare nt material are the consequence of gradually decreasing temperatures d uring their evolution and of oxidation caused by weathering.