Shallow Curie-point isotherm depths, indicated by the analysis of magnetic anomalies, young silicic volcanism, hot springs, and high heat flow mark the Cascade Range of central Oregon as a potentially important geothermal resource area. Aeromagnetic measurements in the central Cascades between 43 degrees 00' and 44 degrees 15'N latitude and 121 degrees 00' and 122 degrees 30'W longitude exhibit predominant northwest-southeast lineations and less prominent north-northeast by south-southeast lineations. Longer wavelength components of the magnetic anomalies (greater than 25 km), possibly related to deeper sources, trend approximately north-south parallel to the Cascade Range. Magnetic anomalies show a right-lateral offset of the High Cascades Volcanism at 43 degrees 30'N latitude, which is consistent with the tectonic structures of the Basin and Range province southeast of the area. Magnetic source depth calculations show that the High Cascades occupy a structural depression or graben on the eastern side of the Western Cascades. Spectral analysis of the magnetic anomalies suggests that the High Cascades are underlain by Curie-point isotherm depths as shallow as 9 km. These shallow Curie-point isotherm depths imply thermal gradients greater than 50 degrees C/km and surface heat flow greater than 100 mW/m 2 .

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