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SUBDUCTION ZONES 261
Figure 9.16 Location map and cross-sections across the Aleutian arc showing earthquake foci (redrawn from Jacob
et al., 1977, by permission of the American Geophysical Union. Copyright © 1977 American Geophysical Union).
5 the adiabatic heating associated with 7 the latent heat associated with phase transitions
compression of the slab as the pressure of minerals to denser crystalline structures with
increases with depth; depth: the principal phase changes experienced
6 the heat derived from radioactive decay of by the slab are the olivine–spinel transition at
minerals in the oceanic lithosphere, likely to about 400 km depth which is exothermic, and
be small as oceanic plates are largely barren the spinel–oxides transition at about 670 km,
of radioactive minerals; which is endothermic (Section 2.8.5).
