| ew or revised heat flow data are presented for 22 sites in and near the transition zone between the stable Colorado Plateau (CP) province and the extending northeastern Basin and Range (BR) province. Where the transition is marked by high elevations, heat flow is often depressed by recharging groundwater. At one site in the southern Wasatch Mountains, two wells yielded a heat flow estimate apparently free of this disturbance. Heat flow at the site is greater than 90 mW m;Other regional geophysical data sets were compiled in an attempt to apply independent constraints to the thermal conditions of the lithosphere. At present, seismic, EM and magnetic data do not resolve deviations of deep crustal temperature from quasi-steady geotherms. Therefore these data do not discriminate between alternative hypotheses for the uplift of the CP and the development of the transition zone. A model of crustal augmentation by magmatic underplating is proposed to explain the seismic velocity structure in the transition. The underplating model is consistent with existing geophysical data and volcanic history, but is not favored over other alternatives.;The other reported heat flow sites are located in the central-western CP and adjacent transition zone. Mean heat flow for this region of the CP is 53... |
