Five representative igneous rocks were analyzed from Hole 1191A. The analytical methods included elemental analyses of total hydrogen and sulfur by NCS (nitrogen, carbon, sulfur) elemental analysis, and the inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for the major element oxides and the trace elements (Zr, Sr, Cu, Zn, Ba, and Y).
Analyses of ignited samples from Hole 1191A and the calculated whole rock compositions are listed in Table T5. The ignited sample results are recalculated with respect to loss on ignition and are used for the compositional diagrams in Figures F10 and F11. The compositions of the samples from Hole 1191A are all similar and compare closely with the composition of the fresh rock samples in two previous holes (Samples 193-1188A-2R-1, and 193-1190C-2R-1) but are richer in SiO2 than 193-1189A-IR-1. In Figures F10 and F11, these three samples are plotted along with the five samples from Hole 1191A. The rocks from Hole 1191A may be classified as dacites both using the total alkalis vs. silica plot (Fig. F10) or using the IUGS (CIPW norm) classification (Fig. F11). In both figures, the sample from Hole 1189A (Sample 193-1189A-1R-1, 0-4 cm) is distinctive on account of its lower silica content relative to the other seven samples, which trend toward rhyodacite compositions (see "Geochemistry" in the "Explanatory Notes" chapter).