Figure F50. A. Total alkalis vs. SiO2 plot with Le Maitre et al.'s (1989) classification of volcanic rock types. Heavy dashed line = division of data for tholeiitic and alkalic lavas of Hawaii (Macdonald and Katsura, 1964; Macdonald, 1968). Values normalized to 100 wt% totals. OJP = Ontong Java Plateau (data of Tejada et al., 1996, 2002; Fitton and Godard, 2004), EPR = East Pacific Rise (data of Sinton et al., 1991; Bach et al., 1994; Mahoney et al., 1994), Nazca-ESC = Nazca Ridge and Easter seamount chain (Ray et al., unpubl. data). B. K2O vs. loss on ignition (LOI). Data for the two carbonate-rich vein samples from Site U1346 are not included in either A or B.
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