Cosmophysical situation in the epoch of the Cambrian explosion

Abstract

Based on available published paleodata, cosmophysical environment of the Earth during the Cambrian evolutionary explosion is considered. Some astrophysical data demonstrate that, about 500 Ma, the Sun entered into the Perseus arm with the enhanced density of star population and spent there several dozen million years. According to some meteorite data, the average level of the galactic cosmic ray (GCR) intensity during that period was considerably higher than previously, when the Sun passed the space between the galactic arms. The GCR flux varied from 25 to 135%, as the Solar System consequently crossed other galactic arms. Some correlation of the GCR intensity variations with periods of global warming and cooling has been found. However, there was no unambiguous relation between climatic data and the GCR intensity. Unfortunately, an accuracy of estimation of the GCR intensity through meteorite data varies to within 0.30-1.5, which does not allow making definite conclusions. For more reliable conclusions, additional astrophys ical data obtaining is needed, and new approaches to modeling of the GCR propagation, which take into account their characteristic lifetime of ~10-100 Ma, should be applied. A possibility of impact of Supernova outbursts and superincreases of solar cosmic ray (SCR) flux on climatic changes are discussed. A possible bio effective role of the geomagnetic field reversals, oscillations of the position of the Sun in the Galaxy, and other unidentified yet factors is also considered.