based on∼600 points per sample. Samples
for geochemical analysis were crushed in a tungsten-carbide ring mill.
X-rayfluorescence (XRF) analyses of glass fusion beads were made
using a Rigaku RIX 2000 instrument at Shimane University, using the
methods described byKimura and Yamada (1996).Rare earth elements (REE) and ultratrace elements (Hf, Ta, Th and U) were
measured in selected samples by inductively coupled plasma mass
spectrometry (ICP-MS), using a VG Elemental PQ-3 at Shimane
University, followingKimura et al. (1995)