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The Geology of Hong Kong (Interactive On-line)
Chek Lap Kok Granite - Jmc

The Chek Lap Kok Granite (Table 6.2) forms a subcircular pluton centred on the new airport at Chek Lap Kok (Figure 6.3). Prior to construction of the airport, the granite was exposed on the western half of the former island of Chek Lap Kok and on the former island of Lam Chau. Exposures are now confined to the area between Tin Sum and Hau Hok Wan on the northern coast of Lantau Island. The type locality is designated as Hau Hok Wan.

The Chek Lap Kok Granite was formerly seen on Chek Lap Kok to intrude the porphyritic fine- to medium-grained Lantau Granite. This relationship is still exposed on the northern coast of Lantau Island at Hau Hok Wan, indicating that the Chek Lap Kok Granite post-dates emplacement of the Lantau Granite.

The Chek Lap Kok Granite consists of an equigranular, fine-grained, leucocratic monzogranite (Plate 6.9). Euhedral to anhedral alkali feldspar is composed principally of mesoperthite. Subordinate euhedral to subhedral albite is unzoned and anhedral quartz is weakly strained. Interstitial late stage muscovite is common along with trace amounts of euhedral fluorite. Biotite, zircon, and Fe-oxide may also be present in trace amounts.

Three zircon fractions from the Chek Lap Kok Granite have yielded consistent results that define an age of 160.4 ± 0.3 Ma (Davis et al., 1997)