Figure 5
From: Genesis of ultra-high-Ni olivine in high-Mg andesite lava triggered by seamount subduction
Ni abundance of olivine in the EC lavas. (a) Olivine of HAB, HMB, HMA, and B. The upper histogram shows the Fo composition of these cores. Colors represent each rock type as identified in Fig. 2. Green field and ochre field indicate compositional fields of Ol that crystallizes from melts in equilibrium with mantle peridotite and pyroxenites respectively23, 24. (b) Ni vs. Fo diagram illustrating linear profile of HMA_Ol with B_Ol. Black lines indicate three types of zonal structure from the core to the rim (Type-1, -2, -3) of HMA_Ol. Type-1 trend reflects ultra-high-Ni Ol explained by fractional crystallization (in 0.1% steps) of Ol and Cpx with proportions of ~3:7 (gray dashed line) from ultra-high-Ni melt at equilibrium with ultra-high-Ni olivine (~6300 ppm Ni)20, 79, 80. This could not be explained by mixing between a mafic component with high Ni content and a felsic component, as observed in the HMB_Ol. Complementary evidence for this model is that the HMA_Ol has no reverse zoning of Fo content and there is no HMA_Ol with low Fo and Ni contents derived from derivate melt. On the other hand, the trend of B_Ol can be explained by fractional crystallization of Ol (gray line) at Fo85–90. Areas surrounded by a green and ochre borders indicate compositional fields of Ol that crystallizes from melts in equilibrium with mantle peridotite and pyroxenites respectively23, 24.
