Ninety-five oriented samples were obtained from nine Recent
Cascade lava flows in Oregon. Directions and intensities of remanent
magnetization were measured on a spinner magnetometer which measures
directions of magnetization to within 1.2° s.d. Angle measurements
were plotted graphically using an equal area projection. Mean
directions and statistics were calculated by digital computer. Samples
were demagnetized in alternating magnetic fields while being rotated in
a two axis tumbling device.
All flow means, except one, calculated from the original magnetization
vectors are distinct from the present geomagnetic field direction.
A correspondence is found between scatter observed in a flow and the
type of outcrop sampled (whether natural or man-made). This is
believed to be a consequence of excessive blockiness and aa characteristics
of the lavas.
Results of demagnetization tests indicate low secondary magnetizations. Stability is indicated by lack of anisotropy, lack of
isothermal and chemical remanent magnetizations, low viscous magnetization,
and divergence of flow means from the present field direction.
Flow mean directions for five dated flows are used to trace the
secular variation of the paleomagnetic field back to 3000 B.P. This
secular variation curve agrees with data taken in southwestern United
States for the same period of time.
It has generally been found that Recent mean pole positions are
coincident with the geographical pole within the limits of error of the
data. This study yielded a mean direction distinct from an axial dipole
direction. However, the age span is limited as eight of the nine
flows have ages between 300 and 3850 years. / Graduation date: 1968
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28223 |
| Date | 24 July 1967 |
| Creators | McKnight, William Ross |
| Contributors | Heinrichs, Donald F. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Relation | Oregon Explorer |
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