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The Geology of Hong Kong (Interactive On-line)
Hok Tsui Rhyolite - Jkh

The Hok Tsui Rhyolite (Table 6.3) is the name given to a swarm of quartzphyric rhyolite dykes that intrudes the Tai Po Granodiorite and the Yim Tin Tsai Formation at Cape D'Aguilar (Hok Tsui) in the extreme southeastern corner of Hong Kong Island. The dykes are up to 10 m wide, strongly flow banded, and strike in a northeasterly direction (Plate 6.12).

The Hok Tsui Rhyolite is the only known representative of a magmatic event that occurred around 152 million years ago (GEO, unpublished data). However, inherited components in four other intrusive units belonging to the Kwai Chung Suite consistently give concordant or near-concordant data with ages ranging from 153.8 ± 0.4 Ma to 149.5 ± 0.4 Ma (Period 2, Davis et al., 1997) suggesting that there was a significant magmatic event in the region at this time.