Table 5.7 - Field and petrographic characteristics of formations in the Kau Sai Chau Volcanic Group
KAU SAI CHAU VOLCANIC GROUP
| UNIT | Clear Water Bay Formation | High Island Formation |
|---|---|---|
| Colour | black to light grey | pinkish grey |
| Composition | rhyodacite to high silica rhyolite | high silica rhyolite |
| Lithologies | lava and crystal-bearing vitric tuff | vitric tuff and rare eutaxite |
| Dominant texture | porphyritic and welded fine ash | welded fine ash |
| Crystals | feldspar and quartz | feldspar, minor qtz |
| Lithics | - | - |
| Glass/Pumice | common | rare |
| Fabric | flow-banded, rare eutaxite and parataxite | massive and rare eutaxite |
| Thickness | >400 m | >400 m |