ORIGIN OF SOLID BITUMENS, WITH EMPHASIS ON BIOLOGICAL MARKER RESULTS

Solid bitumens are allochthonous, non-disseminated organic matter found associated with sedimentary rocks. Common worldwide examples include gilsonite, grahamite and ingramite. Their occurrence in petroliferous basins makes knowledge of their origin of interest to organic geochemists and petroleum explorationists. Using current analytical methods, it is usally possible to assign an origin to these materials, based on chemical characteristcs of the whole material and its extractable fraction. In this study, 27 solid bitumens and their extracts have been studied, and the following analyses were performed: elemental and isotopic analyses of whole bitumen and extracts thereof; pyrolysis-gas chromatography of whole bitumen, and gas chromatography of extractable aliphatic hydrocarbons; carbon-13 NMR aromaticity measurements of the whole bitumen, using CP-MAS techniques; and GCMS studies of biological markers in the distillable hydrocarbons. Results which have a bearing on the genesis of these materials are presented and discussed.