Paleomagnetic secular variation and its influences on environment through the last 150 000 a

Loess-paleosol units S0, L1, S1 and L2, being in the Yangguo loess section, have been studied. Based on the measurements of susceptibility and grain size analyses nonlinear transform function between depth and time has been developed by using Simpson’s integral, and paleomagnetic secular variation records have been obtained through the last 150 000 a. Some geomagnetic excursions or events, occurring in 20600 - 19400, 29100 - 27130, 50700 - 40400, 63500 - 60400 and 127 200-124600a B.P., have been revealed. Spectral analyses of directional records using maximum entropy method show that main periods of inclination and direction are of about 3000, 4000, 6800, 41 200, 2700, 3600, 4500 and 41 200 a, respectively. No obvious relativity can be observed between paleomagnetic secular variation and environmental changes.