Paleointensities of Late Miocene Intrusions from Paiute Ridge, Nevada

Abstract

Shallow intrusive rocks from Paiute Ridge, Nevada, record what is interpreted to be a relatively complete record of a reversal of Earth's magnetic field that occurred approximately 8.65 million years ago. We attempt to verify and expand on this interpretation by determining paleomagnetically-recorded field intensities associated with the paleodirections. Our preliminary measurements show that the ancient field strength was 10-11 microteslas rather than the 50 microteslas that is typical of the latitude of Nevada when Earth's magnetic field is stable. This very low field strength supports the idea that the paleodirections of the samples are anomalous because the field was reversing rather than the rocks being tilted or rotated. Further study still needs to be done with rocks that are younger and older than the reversal, to make sure that all rocks from Paiute Ridge do not yield low paleointensities which would suggest systematic errors.