Understanding heat and groundwater flow through continental flood basalt provinces: insights gained from alternative models of permeability/depth relationships for the C olumbia P lateau, U nited S tates
Аннотация:Heat-flow mapping of the western United States has identified an apparent low-heat-flow anomaly coincident with the Columbia Plateau Regional Aquifer System, a thick sequence of basalt aquifers within the Columbia River Basalt Group. In order to understand geothermal heat flow at the province scale, it is necessary to understand the permeability structure of the upper crust and the resulting coupled heat and groundwater flow. This chapter summarizes two-dimensional (2D) cross sectional coupled groundwater and heat-flow models that demonstrate that, for the most likely distributions of permeability and aquifer tests, the apparent low-heat-flow anomaly in the Columbia Plateau Regional Aquifer System can be explained by accounting for the heat transported to large regional rivers by the groundwater system. The heat-flow pattern is shown to be spatially complex both laterally and vertically, illustrating the difficulties in using the current borehole temperature data set to estimate regional heat flow.
