Figure F9. Downhole whole-rock compositional variation. Note that except for felsic veins/veinlets and samples with excess TiO2 (>0.6 wt%), similar downhole profiles exist for whole-rock Mg#, Ca#, Cr, Ni, TiO2, Zr, Y, and Zn, largely due to mineral compositional variation, which in turn is controlled by the temperature and cooling history of their parental melts. The lack of such a pattern for Sr and Cu is due to modal control. For example, Sr in the whole rock is proportional to the plagioclase/clinopyroxene ratio, whereas Cu is largely controlled by the distribution of sulfide globules.

Figure F9. Downhole whole-rock compositional variation. Note that except for felsic veins/veinlets and samples with excess TiO₂ (>0.6 wt%), similar downhole profiles exist for whole-rock Mg#, Ca#, Cr, Ni, TiO₂, Zr, Y, and Zn, largely due to mineral compositional variation, which in turn is controlled by the temperature and cooling history of their parental melts. The lack of such a pattern for Sr and Cu is due to modal control. For example, Sr in the whole rock is proportional to the plagioclase/clinopyroxene ratio, whereas Cu is largely controlled by the distribution of sulfide globules.