Lyons sandstone

Fig. 25.4. Oxygen and carbon stable isotopic compositions of calcite ( ) and dolomite ( ) cements from Lyons sandstone (Levandowski et al., 1973), and isotopic trends (bold arrows) predicted for dolomite cements produced by the mixing reaction shown in Figure 25.3, assuming differing CO2 fugacities (25, 50, and 100) for the Fountain brine. Fine arrows, for comparison, show isotopic trends predicted in calculations which assume (improperly) that fluid and minerals maintain isotopic equilibrium over the course of the simulation. Figure after Lee and Bethke (1996).

Lee, M.-K. and C. M. Bethke, 1994, Groundwater flow, late cementation, and petroleum accumulation in the Permian Lyons sandstone, Denver basin. American Association of Petroleum Geologists Bulletin 78,217-237. 

Levandowski, D.W., M. E. Kaley, S. R. Silverman and R. G. Smalley, 1973, Cementation in Lyons sandstone and its role in oil accumulation, Denver basin, Colorado. American Association of Petroleum Geologists Bulletin 57, 2217-2244. 

Oil in the small Lyons Sandstone reservoirs along the northwest margin of the Denver Basin has distinctly different characteristics than oil in the Cretaceous reservoirs. The source for the Lyons oil is unknown. The source for the oil in the Lower and Upper Cretaceous reservoirs has been established as Cretaceous shales and limestones (Clayton and Swetland 1980) by oil-to-rock correlation techniques. The Carlile Shale, Greenhorn Limestone,... 

Fig. 2. Columnar section for the Wattenberg area of the Denver Basin. The primary source rocks are the shales and limestones of the Dakota Group, Benton Group, and Niobrara Formation. The most important hydrocarbon reservoirs are the Dakota J Sandstone and the Hygiene and Terry sandstones of the Middle Pierre Shale. The Lyons Sandstone, Codell Sandstone of the Benton Group, and limestone of the Niobrara Formation also produce hydrocarbons...

Fig. 5. Cross-plot of depth versus plagioclase and K-feldspar. The numbers in parentheses are the mean values for plagioclase followed by K-feldspar for each stratigraphic unit. Only in the Lyons Sandstone is K-feldspar more abundant than plagioclase...

Carbonate cement/replacement in sandstones of the Denver Basin is most commonly ferroan calcite based on staining techniques. Dolomite may occur, but is volumetrically unimportant except in the Fox Hills Formation where dolomite (mean of 6.7vol%) is more common than ferroan calcite (mean of 4.5vol%). Ferroan calcite averages 2.8vol% for sandstones of the Middle Pierre Shale compared with less than 1 vol% for dolomite. Sandstones in the two Codell cores are quite different in terms of the amount of ferroan calcite cement, but average 2.1vol% with no dolomite. The Dakota J Sandstone has only trace amounts of ferroan calcite and dolomite cement. The Lyons Sandstone contains trace amounts of calcite and no dolomite. 

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