Figure F5. Total alkalis (Na2O + K2O) vs. SiO2 for Subunits 4A and 4B of Legs 170 and 205. Includes data from Kimura, Silver, Blum, et al. (1997). All samples are subalkaline. Subunit 4A samples have generally higher total alkali content than the majority of samples from Subunit 4B. Note the relatively restricted range in SiO2 and the variability of alkalis at a given SiO2. Also shown are data from Leg 206, the fast-spreading East Pacific Rise deep reference site (Wilson, Teagle, Acton, et al., 2003).

Figure F5. Total alkalis (Na₂O + K₂O) vs. SiO₂ for Subunits 4A and 4B of Legs 170 and 205. Includes data from Kimura, Silver, Blum, et al. (1997). All samples are subalkaline. Subunit 4A samples have generally higher total alkali content than the majority of samples from Subunit 4B. Note the relatively restricted range in SiO₂ and the variability of alkalis at a given SiO₂. Also shown are data from Leg 206, the fast-spreading East Pacific Rise deep reference site (Wilson, Teagle, Acton, et al., 2003).