CARBONATE IDENTIFICATION USING X-RAY DIFFRACTION (XRD) AND CARBON AND OXYGEN ISOTOPE CHEMOSTRATIGRAPHY OF THE RUBY RANCH MEMBER WITHIN THE CEDAR MOUNTAIN FORMATION

Lake Carpenter, located near Moab, Utah is a carbonate-rich lacustrine sequence deposited in the Lower Cretaceous. Lake Carpenter is in the Ruby Ranch Member contained within the Cedar Mountain Formation. Three trenches were sampled at 25 centimeter increments for lithology differences and stable isotope measurements. The beds are correlated between the trenches both compositionally and structurally. X-ray diffraction (XRD) was completed to qualitatively determine the mineralogy of the sequence. Dolomite and calcite have different carbon and oxygen fractionation factors, so the distinction of the samples lithology is key in determining valid stable isotope data. Several samples are both compositionally calcite and dolomite, so thin sections petrology is used to select specific portions of the samples to examine. The sequence fluctuates between calcite, high magnesium calcite, and dolomite until the Dakota Formation is reached. Stable carbon isotopes will provide evidence of the climatic and the depositional setting of the Ruby Ranch Member.