Table 5.5 - General field and petrographic characteristics of formations belonging to the Lantau Volcanic Group
LANTAU VOLCANIC GROUP
UNIT | Lantau Volcanic Group (undifferentiated) |
Lai Chi Chong Formation |
---|---|---|
Colour | bluish grey | black, pale grey, brown |
Composition | rhyodacite to rhyolite | rhyodacite to rhyolite |
Lithologies | lava, vitric tuff and tuffite | crystal tuff, tuffite and siltstone |
Dominant texture | porphyritic, fine ash | coarse ash |
Crystals | feldspar and quartz | feldspar and quartz |
Lithics | - | volcanic rock |
Glass/Pumice | rare | rare |
Fabric | flow-banded, well-bedded | flow-banded, well-bedded |
Thickness | >1700 m | 180 m |