Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow
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Abstract
A new paleomagnetic result from a lava flow with a distinctive, two-part remanence reinforces the controversial hypothesis that geomagnetic change during a polarity reversal can be much faster than normal. The 3.9-m-thick lava (“Flow 20”) is exposed in the Sheep Creek Range (north central Nevada) and was erupted during a reverse-to-normal (R-N) geomagnetic polarity switch at 15.6 Ma. Flow 20 began to acquire a primary thermoremanence while the field was pointing east and down but was soon buried, reheated, and partially-remagnetized in a north-down direction by the 8.2-m-thick flow that succeeded it. A simple conductive cooling calculation shows that the observed remagnetization could not have occurred unless Flow 20 was still warm (about 150°C near its base) when buried and that the 53° change from east-down to north-down field occurred at an average rate of approximately 1°/week, several orders of magnitude faster than typical of secular variation.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow |
| Series title | Geophysical Research Letters |
| DOI | 10.1029/2010GL044286 |
| Volume | 37 |
| Issue | 21 |
| Year Published | 2010 |
| Language | English |
| Publisher | American Geophysical Union |
| Description | L21308, 5 p. |
| Country | United States |
| State | Nevada |
| Other Geospatial | Sheep Creek Range |
| Google Analytic Metrics | Metrics page |