Curie-point isotherm mapping and interpretation from aeromagnetic measurements in the northern Oregon Cascades

• Main Author: Foote, Robert W.
• Other Authors: Couch, Richard W.
• Language: en_US
• Published: 2012
• Subjects: Geomagnetism > Oregon > Maps
• Online Access: http://hdl.handle.net/1957/29323

During the summer and fall of 1982, personnel from the Geophysics Group in the School of Oceanography at Oregon State University conducted an aeromagnetic survey in the northern Oregon Cascades to assess geothermal potential and study the thermal evolution of the Cascade volcanic arc. Total field and low-pass filtered magnetic anomaly maps obtained from the survey data show high amplitude positive and negative anomalies associated with volcanic cones and shallow source bodies along the axis of the High Cascades. Spectral analysis of the aeromagnetic data yielded source depths and depths-to-the-bottom of the magnetic sources. The magnetic source bottom, in the northern Oregon Cascades, is interpreted as the depth to the Curie-point isotherm. The northern Oregon study area shows shallow Curie-point isotherm depths of 5 to 9 km below sea level (BSL) beneath the axis of the High Cascades from the southern boundary (44°N latitude) to near Mt. Wilson (45°N latitude). A smaller region of shallow Curie-point depths of 6 to 9 km BSL lies west of Mt. Wilson (45°N latitude, 122°W longitude). The shallow Curie-point isotherm suggests the emplacement of relatively recent intrusive bodies in the upper crust beneath the axis of the High Cascades and west of Mt. Wilson. A major northeast trending structure observed in magnetic and residual gravity anomalies near Mt. Wilson, is the northernmost. extent of shallow Curie-point depths and high geothermal gradients mapped in the northern Oregon Cascades. This northeast trending structure appears to mark a division between high intrusive activity in localized areas south of Mt. Wilson and intrusive activity confined beneath the major cones north of Mt. Wilson. === Graduation date: 1986