As part of the work I do as a geologist exploring for petroleum, it is very, very important to understand how temperature changes with depth. I was just working in Wyoming. There are more than 122,000 oil wells drilled in the state of Wyoming. Some target oil reserves a few hundred feet under the surface, while the deepest Wyoming oil well is 24,988 feet deep. They take a temperature measurement at the bottom of each hole. EVERY temperature measurement from these oil wells shows that temperature increases with depth. Some of these wells are miles are miles from the nearest fault and there are no tectonic plate boundaries in Wyoming.
You need to reconsider your temperature gradient model, UM.