Stratigraphy: Scattered quartzphyric rhyolite dykes cut the youngest volcanic and plutonic rocks. Little is known about their geochemical characteristics and they have not yet been dated radiometrically.

Distribution: The dykes concentrate in the eastern New Territories, Kowloon, Hong Kong Island and the Po Toi Islands. The dykes vary in trend from northnorthwest to eastnortheast.

Lithology: Quartzphyric rhyolite.

(Strongly Flow-Banded, Quartzphyric Rhyolite Dyke Intruding a Porphyritic Microgranite Dyke. Both Dykes Intrude Medium-Grained Granite, Pak Kok Tsui, Cheung Chau)