251

Geomagnetic Field Effects on Living Systems

FIGURE 6.10 Schematic diagram indicating the late Guadalupian Kamura event documented by high positive

δ¹³Ccarb values at Kamura in Japan. (Isozaki et al., 2007a, modifed from Isozaki et al., 2007b) (a), and the composite

Permian secular curve of δ¹³Ccarb values (modifed from Korte et al., 2005) (b). (a) Note that the Guadalupian large

fusuline and bivalve fauna became extinct in the middle of the Kamura cooling event, whereas the post-extinction

radiation of the Lopingian small fusulines started during the subsequent warming period. In contrast to the wan­

ing history of the Kamura event, its onset timing and processes were unknown previously.

enhance oxygen escape, and this cumulative efect could cause a signifcant drop in O2 level over a few

millions years (Wei et al., 2014). Te reversal rate was increasing and the diversity was decreasing over

the last 40 Ma. Wei et al. (2014) speculated that the present Earth might be experiencing a new gradual

pattern of mass extinction. However, the slight change of O2 level cannot be regarded as a strong link

between them. Wei et al. (2014) proposed that more data and work are required to understand these

variations.