NEW CONSTRAINTS ON UPLIFT OF THE NORTHERN COLORADO PLATEAU

The Late Cretaceous Uinta Basin is located in northeastern Utah within the northern most portion of the Colorado Plateau. The basin's uplift and subsidence history and thermal evolution have impacted the maturity of source beds in the Parachute Creek Member of the Green River Formation. Using measured data of the petroleum system of the Uinta Basin, we were able to constrain timing and amplitude of uplift of the northern Colorado Plateau. We used sixty wells in a basin modeling study of the Uinta Basin’s thermal structure, tectonic history and petroleum system. The wells reached into basement, and four wells provided vitrinite reflectance measurements. Vitrinite reflectance is a measurement of the percentage of reflected light from a polished vitrinite sample. The percentage of reflected light is related to the temperature conditions the sample experienced during burial, and vitrinite reflectance is a maturity indicator that covers a broad temperature range from diagenesis through the latest stages of catagenesis and records the maximum temperature a rock experiences during its burial history.

All models were calibrated to measured data, including vitrinite reflectance and transformation ratios from Rock-Eval pyrolysis. The models predict that the heat flow ranges from 65 mW/m² to 45 mW/m² from south to north in the study area. Additionally, model calibration provides a means for estimating the amount of uplift and erosion in the Uinta Basin. Uplift predicted for the Uinta Basin ranges from ~2050 m to ~2200 m and started in the Late Miocene. Our models also predicted the maturity of the rich oil shales of the Parachute Creek Member.