Fig. 1
(a) TAS classification diagram of Na2O + K2O versus SiO234, (b) LOI concentration (wt%) versus SiO2 for mafic volcanic rocks, which include geochemical reference materials (GRMs), and rocks from Ulleung Island, Baekdusan (Changbaishan) and Jeju Island from Korea and ODP Site 801 C in the Pigafetta Basin, western Pacific Ocean. Mafic volcanics, which include GRMs (yellow solid circles with black outlines) and Baekdusan samples (green solid circles with black outlines) are included in the subalkaline series, whereas most Ulleung Island mafic volcanic rocks (red open rectangles) are included in the alkaline series, except for a few samples. The other samples, including those from Jeju Island, plot in the boundary area between the alkaline and subalkaline series (red dotted line) suggested by Irvine and Baragar35. In the TAS diagram, SiO2 values are recalculated to 100% on an H2O- and CO2-free basis whereas the SiO2 values in (b) are values measured via X-ray fluorescence (XRF).
