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Geomagnetic Field Effects on Living Systems

FIGURE 6.9 Plume Winter scenario for the late Guadalupian event from the core to the surface (Isozaki, 2009,

revised from Isozaki, 2007a). Mantle superplume represents the largest fow of material and of energy within the

Earth. Up-rising hot plumes paired with a down-going cold subducted slabs (megalith) form a large-scale whole-

mantle convection cell. Te launching of a superplume from core-mantle boundary (CMB) was the most likely

ultimate cause of the mass extinction at the Guadalupian–Lopingian boundary (G–LB). (a) In the beginning of

the Capitanian (~265 Ma), the launching of a mantle superplume caused the Illawarra Reversal in the outer core’s

geodynamo and the Kamura cooling event on the surface. (b) In the end the Capitanian (~260 Ma), the impinge­

ment of the plume head at the bottom of Pangea, continental rifing occurred and large igneous provinces (LIPs)

formed to start “Plume Winter.” Trough various volcanic hazards, the G–LB mass extinction occurred, and sub­

sequently long-term oceanic anoxia (superanoxia) started aferward. (Reproduced with permission from Isozaki

(2009), Copyright 2009, Elsevier.)

outer core inside the Earth that can be caused solely by the appearance of a thermal instability on the

CMB, such as launching a superplume.

As shown in Figure 6.9, Plume Winter scenario for the late Guadalupian event from the core to the

surface is presented by Isozaki (2009), revised by Isozaki (2007a).

Isozaki (2009) pointed out that the Illawarra Reversal occurred nearly 5 Myr earlier than the G–L

boundary turmoil on the surface including the mass extinction. Te 5 Myr time lag may represent a

travel time of a superplume from the CMB to the surface (Isozaki, 2009). When the convection is stable,

the GMF strength is high, but when the convection is disturbed, the GMF strength decreases. When