trachy-

The petrography and geochemistry of the volcanic rocks of basalt-chert unit shows that these rocks are basaltic trachy-andesite, trachy- andesite and foidite (Fig.

92 112 118 A B 8a Rock type Basalt Basalt Basalt Trachy- Trachy- Trachy- andesite andesite andesite Plagioclase phenocrysts 3.9 3.5 6.4 11.5 16.5 6.4 Pyroxene phenocrysts 0.0 0.0 0.0 1.1 0.7 1.4 Olivine phenocrysts 0.0 0.0 0.0 0.5 0.9 0.5 Opaque phenocrysts 0.3 0.5 0.7 2.0 1.0 1.5 Plagioclase groundmass 43.7 43.8 37.7 40.7 42.1 44.2 Pyroxene groundmass 25.5 29.5 29.5 8.8 12.8 13.5 Olivine groundmass 3.4 1.9 3.0 0.3 3.3 5.9 Opaque groundmass 22.3 17.9 21.0 6.2 7.6 9.9 Apatite Tr.