Petrographic characteristics and provenance of fluvial sandstone, sunnyside oil-impregnated sandstone deposit, Carbon County, Utah

The Sunnyside oil-impregnated sandstone deposit (Eocene) is located on the southwestern edge of the Uinta Basin. The sandstone is dominantly arkose. Thin section, microprobe and heavy mineral analyses indicate a mixed provenance of crystalline and sedimentary sources. Primary crystalline detritus was derived from southwestern Colorado and sedimentary detritus from locally adjacent Colorado Plateau uplifts. The sandstone at Sunnyside was deposited in a meandering fluvial environment. Lacustrine rocks of the Green River Fonnation overlie and underlie, and are occasionally interbedded with the fluvial rocks. The average paleocurrent direction is N 45° E. The incongruent relationship between the paleocurrent direction and postulated source area is probably due to the presence of the San Rafael Swell upwarp, and the influence upon the drainage pattern by streams that drained the orogenic highlands of western Utah and joined the major northward- flowing drainage at the northern end of the San Rafael Swell. Migration of bitumen into the rocks at Sunnyside occurred after authigenic development of spar-size dolomite rhombs, syntaxial albite and quartz overgrowths, and hematite. Development of calcite cement may be related to the introduction of bitumen. Correlation of bitumen content with textural data was weak. Incomplete saturation of rocks by bitumen prevent a determination of the effect of mean grain size and percent matrix upon saturation.