The paleomagnetic history of the volcanic rocks of Easter
Island was investigated using standard paleomagnetic techniques.
The remanent magnetization of 673 specimens from the three volcanic
episodes recognized on the island were measured using a spinner
magnetometer. Inclinations, declinations and virtual geomagnetic
poles were calculated for each flow. The majority of the samples
were collected from the youngest episode, the Terevaka volcanics,
which represents activity from the last 200, 000 years.
The 65 flows from the Terevaka episode were used to study
the Brunhes epoch on Easter Island. A mean geomagnetic pole was
located at 87.4°N latitude and 204.2°E longitude. With its oval of
95% confidence, this includes the present geographic pole, as expected
for such young rocks.
Secular variation, expressed by the angular deviation of the
mean virtual geomagnetic pole, was obtained for the Terevaka samples,
This value, 12.8° with 95% confidence limits of 14.9° and
11.2°, is compared to other values for Brunhes age rocks. It
appears to fit well onto a calculated model for the variation of angular
dispersion with site latitude. It also can be related to an anomalously
low region of secular variation found in the central Pacific. / Graduation date: 1974
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29263 |
| Date | 29 April 1974 |
| Creators | Isaacson, Laurie Brown |
| Contributors | Heinrichs, Donald F., Blakely, Richard J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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