Palynology and petrography of some solid bitumens of the Uinta Basin, Utah

Several solid bitumens and bituminous substances of the Uinta Basin found in veins, brecciated fissures, cracks, joints, and porous rocks have been examined for petrologic character and palynologic content. Some samples of solid ozocerite, a native wax, intercalated in the matrix of brecciated zones and as crack fillings in the fluvial Wasatch Formation on the southwest side of the basin, near Soldier Summit, contain a large number of spores and pollen. These are of sufficient diversity to indicate Paleoceneearly Eocene age, comparable to the lower Green River palynomorph assemblages of earlier reports. Associated with the spores and pollen are resins, cuticles, and woody tissue fragments of higher plants; fungal sclerotia and hyphae; and some algal entities including occasional colonies of Botryococcus. Present are some vitrinoids comparable to those in the coal beds and shales of associated rocks. The origin of this solid bitumen may be from downdip, time-equivalent lacustrine rocks to the northeast in the lower Green River Formation, but the mechanics of the movement of these palynomorphs out of the source beds into these brecciated fissures and cracks have not been determined. It is probable that coarser, more permeable source beds or reservoir rocks than the typical Green River Shales were intersected by the tension cracks (fissures) which were developing nearly contemporaneously. Gilsonite samples examined contain very few identifiable palynomorphs, and pollen and spores in these coallike bitumens are generally greatly carbonized. A very sparse representation of larger tissue fragments, lower plant spores, sclerotia, and algae is present. Albertite (nigrite) and wurtzilite samples appear to be barren of plant detritus. Bituminous sandstones seem to contain a few palynomorphs, but they could be indigenous to the reservoir rocks and not from the surrounding source beds of shale.