| Description |
The sandstones of the Sunnyside tar sand deposit are composed of detrital minerals and rock fragments (70% of rock), carbonate grains (3%). authigenic cements (St), pores plus tar plus solid bitumen (21%), and unidentified constituents (1%) . The detrital minerals and rock fragments are from most to least abundant: monocrystalline quartz, plaglioclase, potassium feldspar, finer-grained rock fragments, unidentified fine detrital grains, mica, accessory minerals, and chert. The carbonate fragments are from most to least abundant: ostracods, carbonate Intraclasts, and oolites. The rocks are cemented by pressure welding and the following authigenic minerals from most to least abundant: dolomite, calcite. hematite, pyrite, and quartz and albite overgrowths. The sandstones are composed predominantly of fine- to very fine-grained sand. The rocks are well sorted or between moderately sorted and well sorted, and have a slightly compacted texture due to burial-Induced stress. Detrital grains are subangular to subrounded In shape. After deposition the sediments of the Sunnyside sandstones underwent the following sequence of post-depositional alterations: burial and compaction, precipitation of carbonate cements, formation of minor quartz and albite overgrowths, minor dissolution of detrital feldspar, precipitation of pyrite cement, emplacement of tar and solid bitumen, and precipitation of hematite cement. The sandstones contain an average of 6% fines (particles with a diameter less than 0.044 millimeters). The fines are composed predominantly of quartz and feldspar. Fines composed of quartz, feldspar, calcite, and dolomite are created when the rocks are ground or crushed. The amount of fines mechanically produced depends on the duration and intensity of the grinding or crushing and on the size to which the sandstones are reduced. The abundance and types of detrital feldspar, the presence of granitic-gneissic and metamorphic rock fragments, and the presence of plutonic-granitoid and metamorphic polycrystalline quartz Indicate that the Sunnyside sediments were derived from a granitic-gneissic terrane. Ostracod coquina limestones are composed of ostracods and micrite/microspar intraclasts (69% of rock), sparry calcite intergranular cement (13%), intergranular pores and tar (11%) pores and tar within ostracods (6.5%), and detrital grains (0.5%). |
