Thirty-four igneous samples were analyzed by shore-based XRF procedures (Table T2). In addition to all I-1 units, we included a number of basaltic clasts of the C type (e.g., Holes SEG54A, SEG56A, SEG63A, and SEG76A) and one clast from Unit S-1 of Hole SEG64B, strongly suspected to sample the basement lithology at the site. Most of these samples have volatile contents between 0.5 and 1.5 wt% and low Fe2O3/FeOtotal ratios. Notable exceptions are the sparsely to highly olivine phyric samples having volatile contents of 2–4 wt% and Fe2O3/FeOtotal ratios > 0.5. All units are olivine normative and range between mildly nepheline normative to strongly hypersthene normative. Mildly nepheline normative basalt occurs exclusively in the upper series (Table T2).
The majority of igneous units are evolved tholeiitic basalt with Mg# < 0.52 and TiO2 > 1.8 wt% (Fig. F15). Most are in the upper series, where the highly plagioclase phyric units tend to have the highest Mg number and lowest TiO2 content. Basalts with Mg# > 0.65 and TiO2 <1.0 wt% occur exclusively in lower series and correspond to the most olivine phyric units. The available trace element data show marked differences between upper and lower series lavas. For example, Ni (and also Cr and V) is most abundant in the highest Mg number lavas of the lower series (Fig. F15), whereas the incompatible element Zr is most abundant in the evolved basalts of the upper series. Sr is also elevated in the upper series lavas, but this may be because of the high modal proportion of plagioclase in many of these lavas.