Shallow subsurface temperatures and some estimates of heat flow from the Colorado Plateau of northeastern Arizona

Abstract

Temperature data to depths of a few hundred meters were obtained from 29 wells in northeastern Arizona; in the region surrounding the San Francisco Volcanic Field, 8 in the Black Mesa area, and 9 in the south-central Colorado Plateau which includes the White Mountains. Although there was evidence for local hydrologic disturbances in many temperature profiles, most wells provided an estimate of the conductive thermal gradient at the site. A few thermal conductivities were measured and were combined with published regional averages for the north-central part of the Colorado Plateau to produce crude estimates of regional heat flux. None of the wells was accessible below the regional aquifers. To these depths, heat flow in the area of the San Francisco Volcanic Field appears to be controlled primarily by regional lateral water movement having a significant downward vertical component of velocity. The mean heat flow of 27 ± 5 mWm 2 is only a third to a quarter of what we would expect in this tectonic setting. The heat that is being carried laterally and downward probably is being discharged at low enthalpy and low elevation in springs and streams of the Colorado Plateau and Mogollon Rim. In the vicinity of Black Mesa, heat-flow averages about 60 mWm 2 , characteristic of the "cool interior" of the Colorado Plateau. North of the White Mountain Volcanic Field, the average heat flow is about 95 mWm 2 .-3-"SAN FRANCISCO vV"" SSCR %

Physical State and Structure of the Crust Beneath the Western‐Central United States From Multiobservable Probabilistic Inversion

“…In fact, the estimated temperatures are high enough to consider the SFVF anomalously hot in comparison to average continental crust. Moreover, while at first glance it may seem that the relatively lower surface heat flow values measured in this region (likely associated with groundwater flow, Paul Morgan et al, ; Shearer & Reiter, ; Sass et al, ) are controlling our results, this is not the case, as this observable puts only mild constraints on the final thermal structure in comparison to seismic and geoid data. In this context, it has been shown that the effect of compositional heterogeneities on temperature structure within the crust may result in variations of ≥100 °C at middle crustal depths over short distances (Furlong & Chapman, ).…”

The crustal structure of the Arizona Transition Zone and southern Colorado Plateau from multiobservable probabilistic inversion

“…We emphasize, however, that these relative low temperatures in the SFVF area do not strictly correspond to a ''cold'' crustal region; temperatures beneath the SFVF (especially at mid/lower crustal depths) are still high enough to be considered anomalously high in comparison to average continental crust. Moreover, while at first glance it may seem that the low surface heat flow measured in this region (likely associated with groundwater flow [Morgan et al, 2004;Sass et al, 1982;Shearer and Reiter, 1981]) is controlling our results, this is not the case, as this observable put only mild constrains to the final thermal structure in comparison to seismic and geoid data. (Figures 9, 10, 12, and S10) are indicated by dashed lines.…”