Geomagnetic field and secular variations of astronomical parameters

Latest developments and techniques in paleomagnetic research led to obtain more accurate data for geomagnetic variations in direction as well as in intensity in the geological past. Geomagnetic excursions are associated with a dramatic reduction in the intensity of the magnetic field and it’s quick collapse. From the last reverse of the magnetic field in Brunhes chron can be seen several such anomalies, two pics of high value of the geomagnetic field, the first 450 000 years ago and the second about 700 000 years ago. Among them are observed several peaks with low values of the geomagnetic field. Comparing the curve of change of the geomagnetic field and the periods of occurrence of geomagnetic excursions with the curve of solar insolation since the last geomagnetic reverse, can be seen some match changes in the geomagnetic field and the appearance of the ice ages. Serbian scientist Milutin Milankovich set theory on the impact of the three astronomical parameters: the axial tilt, the Earth’s orbital precession and the eccentricity on amount of solar insolation. According to him the secular variations of these three astronomical parameters with periods: ecentricity of 100 000yr. the axial tilt of 42.000 yr. and the Earth’s orbital precession with periods of 19 and 23 000 years could determine the ice and warm periods in the geological past. With the latest paleoclimatic researches the deeper ice cores were drilled and temperature-proxy records that reached further in the past became available (e.g. EPICA community members, 2004). All geomagnetic events during the Brunhes chron may have occurred at times of global cooling which is linked with orbital parameters