Figure 16. Mg number (calculated as Mg2+/Fe2+
+ Mg2+; Fe2+ = 0.85 Fe3+) vs. depth
for Hole 735B. Samples are subdivided mainly on the basis of
TiO2. Filled diamonds = troctolite and olivine gabbro having
less than 0.4 wt% TiO2; half-filled diamonds = gabbro,
gabbonorite, and disseminated-oxide gabbro having between 0.4 and 1.0
wt% TiO2; open diamonds = Fe-Ti oxide gabbro with more than
1.0 wt% TiO2; half-filled squares = felsic samples or hybrid
samples with a significant felsic component. Filled triangle is a sample
from a basaltic dike.