Figure 13. A spidergram for a basalt clast from interval 149-899B-26R-1, 113-118 cm, normalized to primitive mantle and the five common basalt provinces for comparison and source determination. Positive K and Rb peaks are attributed to addition of these elements during seafloor weathering, whereas the negative Sr peak is attributed to removal of Sr with Ca during seafloor weathering. The Ba low and the P peak relative to CFB may be caused by opposite peaks in the typical CFB spidergram (Fig. 10). Less mobile HREEs and HFSEs are parallel to E-MORB and CFB at a value of one, suggesting they are similar to basalts from these environments.