Types of Convection
There is a current debate within the geophysics community as to whether convection is likely to be 'layered' or 'whole'. This debate is linked to the controversy regarding whether intraplate volcanism is caused by shallow, upper-mantle processes or by plumes from the lower mantle. Geochemists have argued that the lavas erupted in intraplate areas are different in composition from shallow-derived mid ocean ridge basalts (MORB). This has been interpreted as their originating from a different region, suggested to be the lower mantle. Others, however, have pointed out that the differences indicate the inclusion of a small component of near-surface material from the lithosphere. Seismologists are also divided, with some arguing that there is no evidence for whole-mantle convection, and others arguing that there is.
Read more about this topic: Mantle Convection
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