Analysis of aeromagnetic measurements from the Cascade Range in central Oregon

Abstract

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°00′ and 44°15′N latitude and 121°00′ and 122°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°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°C/km and surface heat flow greater than [Formula: see text].

Spectral analysis of aeromagnetic data for geothermal energy investigation of Ikogosi Warm Spring - Ekiti State, southwestern Nigeria

“…Thus the Curie temperature isotherm corresponds to the basal surface of magnetic crust and can be calculated from the lowest wavenumbers of magnetic anomalies, after removing the approximate regional field from the aeromagnetic data (e.g. Bhattacharyya and Morley 1965;Spector and Grant 1970;Mishra and Naidu 1974;Byerly and Stolt 1977;Connard et al 1983;Hamdy et al 1984;Blakely 1988;Tanaka et al 1999;Salem et al 2000;Ross et al 2006). …”

Forearc structure in the Lesser Antilles inferred from depth to the Curie temperature and thermo-mechanical simulations

“…Also, as noise in the spectra can affect the quality of the CPD computation, we provide a map of misfit between the observed and the theoretical spectra for each CPD computation window. The theoretical radial power spectrum of magnetic anomalies derived from the shape of the Fourier radial power spectrum, as presented in this study, is derived from the following equation [e.g., Connard et al, 1983;Okubo et al, 1985;Blakely, 1988;Tanaka et al, 1999;Ross et al, 2006]…”

Estimation of Curie point depths and heat flow from Ardebil province, Iran, using aeromagnetic data

“…Okubo et al (1985Okubo et al ( , 2003 suggested the optimal dimensions of the investigated square window to be about ten times the actual target depth (Hisarli et al 2011). Connard et al (1983) divided a magnetic data of the Cascade Range, central Oregon, into overlapping blocks (77 × 77 km) and calculated the radially average power spectrum for each block. Tanaka et al (1999) divided the East and Southeast Asia into sub-region data (approximately 200 × 200 km) and estimated the power density spectra for each region.…”