| Summary: | 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
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