Geothermal studies in the Quemado area, New Mexico

New heat-flow data and K-Ar dates from the southern periphery of the Colorado Plateau (CP) are presented. The radiometric data indicate the area around Quemado, NM was volcanically active during mid- and late-Pliocene time. The heat-flow data suggest a regional value for the area of 75–84 mW m −2, somewhat higher than the non-volcanic regions of the Plateau. The average heat flow in the Quemado area is 10–20 mW m −2 less than the heat flow in the north-western periphery of the Plateau where a transition zone between the Basin and Range Province (BRP) and the CP is present. From geophysical data it appears that mantle upwarping (crustal thinning) is occurring under the transition between the north-western CP and the BRP. From the heat-flow data in the present study it may be concluded that, if crustal thinning is occurring in the southern periphery of the CP, then initiation of the thinning event occurred later than in the north-western periphery of the Plateau; alternatively, thinning may be occuring at a slower rate and/or a greater depth along southern CP. Spatial variability of heat-flow values suggests the presence of upper crustal heat sources and/or ground-water convection.