North-South core-based cross section through the middle to upper Green River Formation, Uinta Basin, Utah - Plate 2

The top of economic oil shale was picked at the top of the lower R-8 zone (top of the Big Three rich oil shale beds). This zone was selected to avoid the abundant saline minerals found in the overlaying saline zone, which often contains high-TDS water. If saline minerals (and high-TDS water) do not adversely affect potential extraction techniques, the top of economic oil shale could be extended to include the middle R-8, but only in the basin's paleo-depocenter. The base of economic oil shale will depend on specifications of potential extraction technologies. Maximum depth might be the base of the R-4 zone. The Mahogany zone (MZ), the richest oil shale zone, and the lower R-8 are dominantly calcareous mudstone, with thin beds of clay-rich and dolomitic mudstone. The upper and lower R-6 zones are dominantly dolomitic to clay-rich mudstones. The R-5 and R-4 zones consist of interbedded organic-rich clay-rich mudstones and organic-lean dolomitic mudstones in ~10 ft cycles. The higher MgO oil shale zones (R-6, R-5, R-4) and the more calcareous, lower MgO (MZ, R-8) oil shale zones will most likely have somewhat different thermodynamic properties, affecting potential extraction techniques. In general, rich zones are thickest and richest in the basin's paleo-depocenter represented by the Coyote Wash 1 core. Thin oil shale breccias are only found in the lower R-8, MZ, and R-6 in the paleo-depocenter of the lake (Coyote Wash 1 and Red Wash 1 cores), somewhat thickening the rich zones in this area. Minor saline mineral depositon occurred within the MZ and A-groove (and upper R-6 in the Red Wash 1 core) in the paleo-depocenter of the lake, possibly due to a lake regression/salinity increase related to the deposition of the organic-lean, dolomite-rich A-Groove (and B-Groove in the Red Wash 1 core). Lean zones are mostly composed of organic-lean mudstone, siltstone, and sandstone and typically thin to the south, except where sand units are present that thicken the section. A significant sand unit is present in the upper R-6 in the south, greatly reducing the economic potential of this unit in this area. This sand unit thins to the north and transitions to a thin mudstone traceable throughout the basin. Siliciclastic-dominated lean zones record periods of high sediment supply sourced from active basin margin delta or mouthbar systems. Carbonate-dominated rich zones record periods of low detrital sediment supply. The large nodule saline facies is only found in the basin's paleo-depocenter (center of cross section), but the small saline crystal facies seems to extend across the basin.