Economic and Environmental Geology

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Fig. 8.

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Fig. 8. (Na2O+K2O)(wt%) vs. SiO2(wt%) plot of the volcanic rocks from Hyeongjeseom, Jeju Island. The fields show rock nomenclature schemes of Le Maitre et al. (2002) with thick solid line from Macdonald and Katura (1964), dividing alkalic rocks from sub-alkalic rocks. Recalculated to 100% on anhydrous basis with Fe2O3/FeO ratio, 0.4 (Middlemost, 1989) prior to plotting. Abbreviations: ThB-tholeiitic basalt, AB-alkali basalt; TBtrachybasalt; BTA-basaltic trachyandesite; TA-trachyandesite. Symbol: open circle from Hyeongjeseom and closed square from Songaksan (unpublished data).
Econ. Environ. Geol. 2021;54:187-97
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