Geomagnetic paleointensity variation with a 100 kyr quasi-period

摘要

We analyzed records of geomagnetic field intensity (paleointensity) during the last 700 kyr in five sediment cores from a wide region of the Pacific Ocean. A global paleointensity variation with a 100 kyr quasi-period was successfully extracted using the wavelet transform. Because the variation does not correlate with that of magnetic properties of the sediments, it originated from a change in the geomagnetic field. The 100 kyr quasi-period of the geomagnetic field is close to the timescales of eccentricity, one of the Earth's orbital elements, and of the glacial-interglacial cycle of the late Quaternary paleoclimate. In particular, there is a correlation between the variations of the geomagnetic field intensity and climate with an 18 kyr time lag. While the geodynamo has widely been thought to be a self -sustained system, our results support the possibility of an external energy supply of the variation through orbital forcing or climate change.