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The Geology of Hong Kong (Interactive On-line)
Shui Chuen O Granite - Kcs


The Shui Chuen O Granite (Table 6.3 ) is the name given to a newly distinguished biotite monzogranite pluton that was formerly part of the Sha Tin Granite. The granite forms an ellipsoidal pluton with the long axis oriented to the northeast between the Sha Tin and Kowloon granites (Figure 6.5), and is centred on Shui Chuen O. The Shui Chuen O Granite is dominantly porphyritic and fine to medium grained, and is commonly weakly deformed. Phenocrysts of perthitic orthoclase and strained quartz are set in a subhedral-granular matrix of strained quartz, weakly zoned plagioclase, and chloritized biotite. Accessory minerals include zircon, apatite and Fe-oxide. A U–Pb zircon age of 144.0 ± 0.3 Ma has been obtained for the Shui Chuen O Granite (GEO, unpublished data).




Details

Shui Chuen O. In typical exposures the granite forms large well rounded corestones and is free from all but very minor quartz veins and aplite dykes (839100 825040 Kcs-1 and 839550 826000 Kcs-2). The contact with the coarse-grained granite south of Sha Tin is steep and complex, striking east northeast. It is interrupted by numerous sheets of quartz monzonite and fine-grained granite.


Tai Shui Hang. The medium-grained granite around Nui Po Shan (840500 828500 Kcs-3) and northeast of Tai Shui Hang (841800 829600 Kcs-4) is generally homogeneous and equigranular. In Turret Hill Quarry (840100 827550 Kcs-5) it is intruded by thin sheets and dykes of fine-grained granite, and in places has an intersitial fine-grained texture. Northeast of Tai Shui Hang the medium-grained granite is cut by fairly flat lying sheets of fine-grained granite. Although the medium-grained granite shows few signs of grain size modification, the contacts are rarely sharp; patches of fine-grained granite occur within the medium-grained granite (841730 829930 Kcs-6).